History of Plessey by Plessey
History of Plessey by Plessey/Tellumat

Plessey History

Foundation of the Plessey Company
The history of Plessey and the story of the radio, electronics and telecommunications industries are so closely bound together that in tracing one, the developments of the others must also be recorded.

Equally, the story of Plessey has running through it a single strand of continuity - the contribution of the Clark family - Grandfather Byron, father Allen (later Sir Allen), and sons John and Michael.

To mention a few names is invidious; and it is impossible to mention all who made the company (first registered in 1917 with a share capital of £1,000) grow into one which in 1983 has issued capital of some £120M and annual sales (1982/3) of some £1 ,075M. But the result of their joint and several achievements - 130 factories and other major operations in North and South America, Southern Africa, Australasia, Europe and indeed all over the world, are there for all to see.

The Beginning
The story starts at the outbreak of the first World War with a young man called William Oscar Heyne. He was a good business man and a brilliant production engineer. The war made it difficult for the young Heyne, as he was born in Germany. He was interned for a time but was released on the condition that he got a job of 'national importance'. It did not prove easy for him to get a job at all but he finally got work with a firm of woodworking machinery makers. From there he moved to a business in Lisson Grove, Marylebone (London) - the Coutsam Piano Action Company. It was in financial difficulties and was bought by a Thomas E Hurst-Hodgson, who soon realised that he must liquidate the company but that Heyne was one of the major assets. He formed a new company to take over Coutsam's machine shop.

That company was The Plessey Company Limited, registered with limited liability on 11th December 1917, with nominal capital of £3,000, although only £1,000 was of shares issued for subscription. The shareholders were Heyne, Hurst-Hodgson and two brothers, Raymond and Plessey Parker.  A friend of Hodgson, Bryon George Clark also bought 640 shares.

Whence the name Plessey?
There was a coincidence that not only was one of the shareholders named Plessey, but Heyne's wife Elizabeth came from the locality of Plessey in Northumberland (in the north of England). The name was a good one, could be pronounced in any language, it sounded well and left the scope of the company open.

The word Plessey itself is a place name of Old French origin. It occurs in a number of forms - Plessis in Brittany, and notably Pleshey in Essex, which means 'place enclosed by a hedge of plashed or pleached', that is, interwoven branches. 'Pleached' is a word that Shakespeare uses too.

According the the original Memorandum of Association, Plessey was in the business of machine engineering, as well as making pianofortes, organs and musical instruments. It certainly made jigs and tools, but there are no records that Plessey ever made a piano or organ!

First Hurst-Hodgson and the Parker brothers were bought out, Heyne and Davieson becoming the directors, and Plessey moved into Cottenham Road early in 1919.

These premises were shared with another business, Shiner and Metal Platers, and Grandfather Byron G. Clark was associated with this company. After a year or so, B.G. Clark decided he liked the look of Plessey and Heyne, and offered an injection of capital. He also saw it as an opportunity to launch his son into a career. A share holding was taken up in the name of A.G. Clark in February 1921, and A.G. went to work for the company six months later, in September of that year. The key partnership between Bill Heyne and A.G. had begun. Heyne, at the age of 32, was Chairman and Managing Director; A.G. Clark, then 22, was secretary. The Company occupied two rooms, with lathes drills and other machinery, and made jigs and tools. Turnover in 1921/22 was £4,000. Heyne earned £8 per week and A.G. £4. The year end result was a loss of £69 - following a previous year - end loss of £206, things were moving in the right direction!

The story of Plessey thereafter is one of essentially continuous evolution and growth, moving progressively into whatever at the time was then the latest technology to be emerging. In 1922, in anticipation of the formation of the British Broadcasting Company (predecessor of the present day BBC), A.G. Clark was the leader in establishing the British Radio Phone Company (a subsidiary), set up to tender for bulk deliveries of radio sets, the intention being to sub-contract the manufacture to Plessey. The company won a contract with Marconi for an order of £30,625.  He was outstandingly successful, collecting orders for 10,500 radio receivers in 1922 alone.

The company also an order from Marconi for 500 'Junior' Crystal sets, 5,000 'A' crystal sets, and 5,000 'V2' receivers. As a result Plessey moved to a larger factory in 1923. Around the same time, Marconi founded a subsidiary company, Marconiphone to handle the distribution of its receivers.

By 1924, 80% of Plessey's turnover came from work for Marconiphone, and so Plessey had to agree when Marconiphone decided to buy shares in the company, and nominate two directors. The following year saw the formation of Plessey (1925) Limited.

In 1926 Marconiphone acquired its own manufacturing company, Sterling Telephone and Electric, at Dagenham. As a result it sold its Plessey shares, and its two nominees left the board. The contracts with Plessey soon ended, and so Plessey had to quickly find alternative orders. As a stop-gap, Plessey designed the 'National' five valve portable receiver, which would be sold as a kit to the Symphony Gramophone and Radio Company, and the Columbia Graphophone Company.

Marconi also produced an almost identical receiver, the Marconiphone '55' using Plessey components and a similar circuit board.

This progress continued throughout the 20's, with progressively greater involvement in radio and, at the end of the 20's culminating in the first production run in the world of television receivers to the recently invented design of John Logie Baird, for whom Plessey made televisors in quantities for the world's first broadcast TV service, established by the BBC experimentally in 1928, on a regular basis in 1929 and continued until the adoption of high definition TV in Britain in 1936. Plessey continued in the manufacture of radios for domestic use and later, car radios, and was the largest European manufacturer of TV receivers over many of the post WWII years. A.G. Clark took the view that Plessey was primarily a first rate manufacturing company and left the selling under various brand names to other companies to whom Plessey was a sub-contractor.

Expansion of the business necessitated a move to larger premises, and this took place with a move to Vicarage Lane, in Ilford, Essex, some miles to the east of London proper, although forming part of the Greater London conurbation. At the time of the move the Vicarage Lane site was up for sale for a reported £20,000 and Heyne was surprised when his offer of £7,500 was accepted. At the time the site contained only a small two storey building and a few huts, but has since been completely covered with mainly multi-storey buildings.

The Ilford site became and still remains the legal head office address of Plessey, now correctly known as The Plessey Company plc (public limited company, the official title of a company quoted on the Stock Exchange and whose shares are traded in generally). Still further expansion took place, the Ilford site gradually being filled up as business grew, with the move into various electric activities - what are now known as 'electronic' components, aircraft electrics, wiring harnesses, telephone instruments and an ever widening range of sub-contract work in the mechanical radio and electrical areas of business.

The War Period
As a result of this manufacturing expertise, Plessey was well placed to take a key role in war-time production of radios, starters and a whole host of aircraft equipment items for WWII, and to add to space available for production as well as to provide continuity of manufacture in the period 1940 to 1942, when air raids on London were at the height, took over a 5 mile section of the Central Line tunnel, intended to extend the London Underground railways into the eastern suburbs of London, and constructed just before the 1939 WWII broke out.

This 'factory in a tube' was some 13 feet in diameter, entered only by stairways at the locations planned for stations when completed, and at peak, over mile or so long probably the world's longest and thinnest factory ever!  The working area amounted to 300,000 sq ft and used 350,000 Watts of lighting.  There was also 7 million BTU's of heat to be dispersed of as well.

The company also took over factories at Cardiff and Swindon.

By the end of the war Allen Clark had become Chairman and Managing Director, a position he held until 1942.  The labour force stood at 11,000, compared with 5000 in 1939.

Post WWII recovery
Peace brought a run down in employee number, which fell to 7,000 in 1947.  But wartime experience with classified navigation aids, radar, and a whole host of aircraft radio and other systems pointed the way for Plessey to expand into previously undreamed of fields of activity in the recovery from wartime conditions. In the immediately post war years there was plenty of demand for radios and TV sets, and the defence electronics businesses, reinforced by wartime know how, formed the basis of Plessey expansion in the 50's, with more moves into vertical integration based on component and semiconductor manufacture.  They also started to produce traffic signals.

The need for diversification
It was becoming clear that there would be a need for a much more fundamental diversification if business growth was to continue, and in 1961 Plessey made an offer to acquire the entire share capital of Ericsson Telephones Limited and The Automatic Telephone and Electric Company Limited, and then to merge them into a new grouping embracing the whole spectrum of defence and civil electronics and communications.

Before looking at the consequences of this merger, it is first necessary to look at the rather longer back start of what became the telecommunications interests of Plessey.

Plessey backgrounds in telecoms
The origins in telecommunications go back to 1884, when two brothers, J and G Crosland Taylor, founded the Telegraphic Manufacturing Company in Liverpool.

The ‘Telegraph Manufacturing Company’ opened a factory in March 1887 at Helsby in Cheshire.  This was not their first factory as that was at Neston in the Wirral which opened in 1882.  George Crosland Taylor had moved to live nearby in late 1881 from Huddersfield.

Some ten years later, in the heyday of the old 'National' Telephone Company, a warehouse was opened in Nottingham through which the needs of the 'National' for telephones and other items of apparatus were met by supplies imported from the L M Ericsson Company in Sweden. This was followed by local assembly, later moving to Beeston in 1903 to premises vacated by the Humber Cycle Company, with the formation of the British L. M. Ericsson Manufacturing Company.

The company persuaded the GPO to install automatic exchanges  at Epsom & Headquarters (London)  in early  1911 and it was in November 1911 that they decided to form a separate company to take over their Edge Lane Works (Liverpool) as a subsidiary to look after the automatic interests. 

The new company came into being the 1st January 1912, with the formation of the Automatic Telephone Manufacturing Company (ATM), established in Liverpool to make the Strowger system under licence from the Automatic Electric Company of Chicago. The aim was, of course to serve the Post Office, which had exercised its rights to take over the National company after 20 years of legal battles. The establishment of ATM, later ATE, was the beginning of now well over 70 years of production on the Edge Lane site.

With the growth of business after the 1914/18 War, automatic systems soon started to replace manual switching, and this was greatly accelerated by the invention at Liverpool of the Director system for routing calls to destination exchanges through networks of many other exchanges in large cities. By many the middle 20's, such systems were spreading rapidly throughout Great Britain, and were starting to be exported to countries in the then British Empire and elsewhere.

There was, at this time, little possibility of ATE or ETL becoming a major supplier in transmission systems to the home market, divided as it was between strongly entrenched manufacturers. ATE established a range of transmission systems aimed at export, and it was with these that the first links were set up with Stromberg-Carlson. Although the relationship was informal, and for over 20 years remained so, it was the basis of the mutual regard and respect leading to the overtures from Plessey which led to the acquisition of S-C into Plessey Group in 1982.

The Merger
However, returning to the 1950's, British progress towards the 'ultimate' all electronic system had reached the stage of field trials of embryonic systems when, in 1961, the merger between ATE, ETL and Plessey took place, giving Plessey a major share of the British telecoms market. The early 60's were really the crossbar era, when in Britain Plessey 5005 crossbar was adopted as a British standard, also being made by GEC, into which the former AEI company had been merged.

The events of the early 60's were overshadowed by the illness and the death of A.G., by now Sir Allen Clark. It was at the very moment of his triumph in re-arranging the whole British electronics and telecoms industry that he became seriously ill and was shortly afterwards unable to take any further part in the Company's affairs, passing away less than a year after the offer which led to the Plessey - ATE - ETL merger.

His place as Chairman was taken for an interim period by Sir Harold Wernher (1962/1963), former chairman of ETL. In due course, he was succeeded by others, and finally A.G.'s elder son John, now Sir John Clark, became Chairman in 1970. Plessey has been fortunate in its successive Chairmen, each of whom has contributed his own touch and style, but all pointing the company in the same upwards and forwards direction.

In the early 60's telecoms started to look seriously at electronic systems to replace the century old electromechanical systems. The first serious trial of an experimental all electronic system took place at Highgate Wood in 1962, with Plessey companies playing a key role.

Part of Decca Radar was bought in 1965 including the ground to air interests.   But rapid growth in size since 1960 brought problems of rationalisation.  So in 1965 Plessey engaged the McKinsey Group to report on the problems.  The final solution was to create a number of groups within the business.  Each group was basically autonomous and had it's won R&D centre.

Plessey made acquisitions in the USA of Allied Unlimited and Plessey Airborne.  With hindsight these were probably made at the "wrong" time - from a financial standpoint.

1971 saw the group structure disbanded in favour of product based business units.

From this first step, our Beeston site developed what became known as TXE2 (for British Post Office use) and Pentex (for export). This was a reed relay switching system with a programmable electronic control, and rapidly filled a gap in the range of modern systems, being installed in over 30 countries and made additionally by the other British switching system manufacturers, with now over 2,000 exchanges in service worldwide. Related technology was also used in TXE4, still being made by Plessey for British Telecom.

The export success, in particular of Pentex, led in 1978 to the award to Plessey of the Queen's Award for exports, particularly gratifying in view of the common assertion that the British telecommunications industry is not export oriented. This export success was linearly related to Plessey companies' expertise in interworking and signalling, gained over many decades in territories all over the world.

For the old ETL and ATE companies this had ensured easy access to world markets with older systems, and the accumulated experience so gained enables future systems to be designed in Plessey versions which incorporate such interworking features as an inherent aspect, rather as in so many other systems as bolt-on applications.

No less significant is the parallel development of semiconductor technology in support of the main stream system development. Plessey Research at Caswell is well up among world leaders in the newer material and device technologies, and is prototyping many new 'chips' of special significance for the new telecoms systems and equipment projects. This parallel activity has had its greatest impetus since the general move towards totally digital systems, initially in transmission equipment for junction circuits, later for both long distance and local links, now into switching centres and ultimately right down to and inside the subscriber's telephone.

A further change in technology, which will be at least as significant as the first moves a century ago from manual to automatic systems, is that represented by the ever widening use of micro electronic devices in control systems, at first as control computers having overall control of functions such as call routing for long distance subscriber dialled calls, with which we in 1960 played a leading part in the introduction of magnetic drum and ferrite core based systems in U K and which, in micro-electronic versions now form the heart and mind of exchange switching systems.

Early automatic telephone exchanges operated in accordance with a set of control logic elements - usually in the form of groups of relays - in which the control action was fixed in its nature and determined by the pattern of wiring and interconnexion within the relay groups. Experience with the first primitive computers in the middle 50's suggested that the greater flexibility provided by the ability to 'program' such computers could be turned to good account in providing additional flexibility and new services in telephone switching systems, by the use of such computer like control complexes in place of earlier, conventional control logic.

A most important aspect of such a change is the question of system reliability and the need to recover automatically from fault conditions and from accidental or fraudulent mis-use - early computers were all too well known for their capacity to 'crash' in the middle of a vital run! The earliest electronic switching systems were no exception to this. The first really successful application in UK of electronic control in such systems was in Plessey Pentex, which at first used electronics in a wired logic mode, but increasingly evolved towards stored program control as ever wider applications occurred for Pentex in export markets. This would have led in due course to a fully stored program version had it not been for the parallel development of digital technology for switching as well as for control.

These further evolutionary steps in the uses of digital technology for switching, control and other applications has led to System X, one of' the world's most forward looking system in its potential to adopt progressively developing technology whilst retaining a stable system architecture. It has a key role in the emergence of a new digital network which will serve Britain and other countries well into the next century, with its ability to handle speech, data and information of all kinds, giving users a better and quicker service, many new facilities and options. Plessey, at first just one member of the joint development group charged with System X planning and early development, was appointed prime contractor in 1982 for the further development of System X, with GEC as sub-contractor, and is additionally producing UXD5, a small system compatible at network level with System X and able to provide the most modern services and facilities to users in remote, rural and small town locations.

At exactly the same time as the announcement of Plessey as prime contractor for System X, it was also announced that Plessey had acquired the public switching business of' Stromberg-Carlson in the United States. The significance of this for both parties is very great - the support of a major telecoms manufacturer for Stromberg-Carlson. The importance of' the new association for Plessey is in support of its determination to use this acquisition to spearhead and grow Plessey presences in both the public and private sectors of the world's largest telecoms market place.

Digital technology is, inevitably, playing a major part in transmission system developments. As far back as 1958 a field trial of a Plessey digital transmission link was established in the Reading area, and the introduction of fibre optics technology will still further accelerate progress towards a totally digital network. Since July 1982, a Plessey digital system using a fibre optic link has been operating between London and Birmingham, the world's longest system of this nature, and by July 1982 Plessey had won over 55 of all BT contracts for such systems. There is no less significant an involvement in satellite links; in January 1983 Plessey formed a joint company with Scientific Atlanta to exploit satellite and cable communications markets.

Equally significant has been Plessey activities in defence electronics. Apart from the acquisition of the former telephone companies ATE and ETL, Plessey also acquired the defence business of Decca, the British radio, TV and gramophone record company. This brought in a substantial military/defence capability to supplement Plessey expertise gained from wartime and post war developments in military radios and pack sets. From war-time experience of then secret airborne navigational aids came a range of avionic systems, later supplemented by the acquisition of the avionics business of Standard Telephones and Cables, the former UK ITT company but now only part owned by ITT.

Inevitably, with a defence involvement, much of Plessey work in the PESL area is security classified and able to be disclosed on a need to know basis for each specific contract.

Among those activities to which reference may be made are projects BRUIN, a semi-mobile communications network for the Army in Germany, its data counterpart WAVELL, the successor PTARMIGAN, a fully encrypted digital mobile cellular radio communications network able to provide instant secure channels between generals at HQ and staff officers in mobile headquarters or, for that matter, to the private soldier in his foxhole! Many of the principles established for reliable telephone and data switching embodied in such projects are derived from civil research work on reliable systems done as part of Plessey Telecoms programs.

In addition, and as a result of further synergy between Plessey businesses and Plessey Research at Caswell, PESL has developed a series of radars, including very advanced 3D systems which employ high technology forms of signal processing by Surface Acoustic Wave (SAW) techniques to enhance the performance and resolution of the systems and displays.

Basic data as at March 1977
Turnover - £568.8 Million
Number of establishments - 130 in the UK and 250 worldwide.
Capital Employed - £319.2 Million.
Number of UK employees - 48,182.
Average wage - £3150.
Profits before tax - £39.6 Million.

The underlying theme of Plessey strategy
Insofar as a company with interests as widespread as Plessey can have a single strategy, it is that Plessey will grow in profitability and size by tackling new technologies as soon as it is possible to do so, setting up new business activities to exploit the new ideas as soon as a sound business plan can be erected.

Similarly, older activities are kept under continuous review for their 'survivability' - balancing the need to confine the entire gamut and range of businesses encompassed to those which can be managed efficiently, against the need to move continuously into new business areas, and deciding for each in turn whether and when to make a drive towards new systems and products, to pull out of older systems (or perhaps to become the last remaining supplier of a specific older system so as to pick up all the extension and replacement orders.)

Such consideration led to the negotiations as a result of which in 1982 Plessey was appointed as lead contractor for the further development of System X, referred to above, with GEC Telecommunications as principal subcontractor. With GEC, 6 system X exchanges are already in service, growing to 14 scheduled by the end of March 1984. 43 local exchanges (plus 158 remote concentrator units to a total of 345,000 lines) together with 26 trunk exchanges (total capacity of some 65,000 erlang) are scheduled by the end of March 1985. By 1986/87, Plessey and GEC, competing for the contracts, are scheduled to have completed over two million lines installed and in service.

Similar reasoning, and even more recent in time, is being adopted in the move towards new systems and products within Plessey Office Systems, also involved in its first drive into the U S A marketplace.

In conclusion
The above notes are intended to serve only as a guide and background to those Plessey staff interested in how we got to where we are. Several experts have already attempted to record Plessey's history, and most of the accounts disagree vigorously!

These notes were undated and have been updated as additional information was made available.

The original Helsby Works in 1887


A few weeks before the building was demolished in mid-2008
and now just a housing estate & Tesco store

The history of Plessey / Tellumat

1917:  The beginning
The origins of PLESSEY began with the career of W.O. Heyne, a German by birth, who lived in England from the age of four. He trained as an engineer, but in 1914 was interned in the Isle of Man, and not released until 1916 on the proviso that "he found work of national importance". He joined a London company manufacturing woodwork machinery, producing structural members for aircraft, but soon moved to the Clutsam Action Company, manufacturers of piano-forte actions. Demand for their product was limited and the owner, Hurst Hodgson, decided to sell the company. However, realising the potential engineering skills of W.O. Heyne and to give these greater scope, he formed a new Company called PLESSEY on 11 December 1917.

The Memorandum and Articles of Association defined the objectives of the new Company to be "machine engineering and machining and manufacturers of piano-forte actions, piano-players and musical instruments of all kinds". From this inauspicious beginning the history of the PLESSEY Company began. The new company had a nominal share capital of £3,000, of which only £1,000 shares were issued and divided between Hurst Hodgson, Mr C. H. Whittaker, a school friend of Heyne who held them on his behalf as he was still technically an alien, and two brothers, Raymond and Plessey Parker. The names of these original shareholders provide a clue to the unusual name of the company, in that one of the shareholders was called PLESSEY, and Heyne's wife, Elizabeth, came from the village of the same name in Northampton - co-incidence dictated the choice. Furthermore, the name sounded well and left the scope of the company open. The first PLESSEY factory was in Marylebone and consisted of shop premises and a large greenhouse in the back garden. Hurst Hodgson also had an interest in British Electro Chemists Ltd, which Heyne joined as a salesman and then took over for PLESSEY.

In 1919 the company was reorganised, Hurst Hodgson and the Parker brothers were bought out and PLESSEY moved to new premises in Holloway. These premises were shared with another business, China Metal Platers, with which B.G. Clarke was associated. He quickly recognised Heyne's engineering ability, coupled with the potential for PLESSEY to grow if more capital was available. The February 1921, B.G. Clark put money into the company, and in September his son, A.G. Clark, began with PLESSEY - the key partnership and basis for PLESSEY's future growth had begun. Heyne, at 32, was Chairman and Managing Director and A.G. Clark, aged 22, was the Secretary, with four other directors and a workforce of between four and six people. The company occupied two rooms and made jigs and tools: Turnover in 1921 / 1922 was £4000, on which was made a small loss of £69. This was followed by a profit of £206 which showed that PLESSEY was moving in the right direction.

1922:  The radio era
In 1922 PLESSEY obtained an immensely important order which was to transform the company. B.G. Clark, who lived in Reading, commuted to Paddington, and two of his travelling companions mentioned to him that Marconi were looking for firms to manufacture radio sets under contract. The three friends saw the potential and formed the British Radiophone Company specifically to tender for radio orders, which they hoped to sub contract to PLESSEY. In July they won the order worth £30,000 for 5,500 Marconi crystal sets and 5,000 V2 valve receivers. PLESSEY therefore entered the radio industry at a very early stage.

New premises were soon essential and Heyne heard that a factory at Ilford was for sale for £20,000. With B.G. Clark, he viewed the factory and offered £7500 which, to their surprise, was accepted: PLESSEY left London in March 1923 and in 1925 the original company was wound up and the PLESSEY Company as the modem company was formed, this time with a share capital of £20,000. In the new Articles of Association, reference to pianos and musical instruments was omitted. The building purchased by PLESSEY was originally a laundry but during the First World War this changed to the production of shells and aeroplane components. After the war tyre studs were made for Dunlop but this venture was never successful and the factory remained empty from 1921 until purchased by PLESSEY.

By early 1925 PLESSEY was selling 1,300 sets a week to Marconiphone, the company set up by Marconi to handle radio receivers and, by September, this had increased to 2,500 sets. In 1926, orders from Marconiphone ceased when they bought their own manufacturing company, Sterling Telephone and Electric, at Dagenham. To provisionally fill this sudden and serious gap, the company designed the first portable radio called the National. Success with their sets resulted in orders from other companies such as Symphony, Eunello; Columbia, Defiant and Sparta, for manufacture of their radios. PLESSEY also obtained orders from the Post Office for belts, buzzers and lever keys and later, in 1929, candlestick telephones. Thus began our long association with the Post Office and our future investment in telecommunications. Admiralty's order at this time for wireless with its telephony components started PLESSEY's connection with the Armed Forces.

In 1927 Henry Morgan became Chairman and continued in the role until 1944.

A further indication of the varied list of products made by PLESSEY was a totalisator for Cardiss Racecourse and the Jenson cigarette lighter which; in 1928/9, provided 8% of turnover. PLESSEY was also involved with early television experiments and Logie Baird worked for a time at Ilford conducting experiments from the roof of this factory. Within the Exhibition Room at Ilford, Stookie, the original dummy's head used by Baird, can be seen with one of the original televisions.

A particularly significant product at this time was the AC44 Airborne Transmitter Receiver, one of which was flown in an Airspeed Envoy in the 1934 International Air race to Australia. This was the forerunner of the TR9 communications equipment for fighter aircraft for which important Air Ministry contracts were obtained later in the 1930's. These products marked the commencement of PLESSEY's involvement in Defence communications.

1930:  The war years
Throughout the 1930's licensing agreements were a major pattern of growth and A.G Clarke and Bill Heyns made annual visits to the United States and obtained vitally important licences from Breeze, Koffman and Pesco. Breeze was a comprehensive system of wiring to prevent radio interference. The Koffman licence was a cartridge starter which gave a burst of gas pressure to spin the aircraft engine for a "scramble" takeoff, and the Pesco licence covered aircraft fuel pumps. The technology was later developed by PLESSEY and laid the foundations for the later aerospace and hydraulics business. Turnover in 1936/37 exceeded £1 million for the first time, and on 17 March 1937, PLESSEY became a public company.

In 1939 PLESSEY was well placed to play a key war-time role, but space was at a premium. However, the space problem was solved by setting up factories at other sites away from London and by using the nearby Central Line tube between Gants Hill and Wanstead, which had been completed but not opened just before the outbreak of war. In this tunnel, with a total length of 5 miles, 2,000 people were continuously at work and it became the most successful underground factory in the country. The factory was 300,000 sq. ft. in size, used 350,000 watts lighting and 7m B.T.U.'s of heat was dispersed.

The war effort of PLESSEY was considerable, totalling 18 million shell and bomb cases, 11 million Breeze connectors, 28 thousand aircraft pumps, 74,000 wiring harnesses and 23,000 engine cartridge starters. When the war finished the massive turnover dropped dramatically and sales to the Government of £5 million in 1944/5 had shrunk to £1/4 million in 1946. The workforce fell from 11,540 to less than 6,000 and in 1946, B.G. Clark died and B.N. Heyne retired.  Allen Clark became Chairman and managing Director, a position he held until 1962.

1950:  Growth into Telecommunications
The company looked again to the growing commercial radio and television market for increased sales and then, with the onset of the cold war, defence products were again in demand. In the 1950's PLESSEY put increasing emphasis on R&D and re-established itself as an important supplier of defence communications.

In 1961 the size of PLESSEY doubled overnight when the company bought out A.T. & E and Beeston Ericsson which brought in a large proportion of Post Office business, together with overseas business establishments and a diversity of new products. it was at this crucial time in 1962 that A.G. Clark died, but the challenge was met and the company continued to grow, often by acquisition which included consolidating our position overseas. Telecommunications now became of great importance and PLESSEY were U.K. Company with electronic switching and alone with an export exchange called Pentex.  The workforce rose to some 17,000 and by the late 1960's this had become 73,00 mainly due to take-overs.

Sir Harold Wernher became Chairman for 1962/1963 and was succeeded by the Earl of Kilmuir who held office until 1967.

1963 :  South Africa
It was with the acquisition of A.T. & E and Ericsson that PLESSEY came to South Africa as they gained the South African subsidiary 1963. Instrument Manufacturing Company (IMC) was also bought out in 1964, and all activities were consolidated at IMC's factory in Cape Town.  In 1974, 26% of PLESSEY South Africa's equity was sold to SANLAM with first right of refusal to further equity. The share holding was subsequently transferred to Sankorp, Santam's industrial holding company.

In 1965 the company addressed the problems of rationalisation.  The McKinsey group were hired and assisted in creating a number of groups (Components, Electronics, Dynamics, Telecommunication, International and Automation).  Each group was basically autonomous and had their own R&D centre.

In March 1966 the company sent a letter to all employees indicating that the Post Office was about to undertake a massive expansion of it's telephone system.  Plessey would be involved in the production of ATE "5005" and Ericsson Pentex equipment.  The Telecommunication group would therefore need to expand it's workforce by 17,000 extra people.

Lord Harding was Chairman for the period 1967 to 1970 and was succeeded by7 John Clark in 1970.

The company made acquisitions in the USA of Alloys Unlimited and Plessey Airborne.  With hindsight these were probably made at the wrong time, financially speaking.

In 1971 the "Business" structure was established with the disappearance of all group structures, except Telecommunications.

As of march 1977, the Turnover was £568.8m, Capital employed was £319.2m, the number of employees was 48,182 and the profit before tax was £39.6m.

When the PLESSEY Company was taken over by GEC-Siemens in 1989, Sankorp indicated its wish to purchase the 74% shareholding it did not own. After two years of protracted negotiations, PLESSEY became a wholly owned subsidiary of Sankorp under the new name of PLESSEY SOUTH AFRICA LIMITED. The addition of the name Tellumat had a double symbolism, firstly for the company's commitment to exports, as it is the name of its UK based export subsidiary. Secondly the name derives from the Tellurometer South Africa's world first electronic surveying development - and by implication a commitment to ongoing electronic research and development.

The merger from April 1st 1995 of PTSA with Tek Electronics, the consumer electronics audio and video products, manufacturer and distributor, (also wholly owned by Sankorp) took PLESSEY full circle back to its consumer electronics roots. This resulted in the renaming of PLESSEY back to the original name of PLESSEY SOUTH AFRICA LIMITED. At the end of 1996, Plessey sold off the Sales and marketing business of Telefunken, Pioneer and Satellite TV. In October 1997, PSA launched on the JSE (Johannesburg Stock Exchange). Trading started off at R4.80 a share.

1996:  The Fire
On the evening of the 6th of February, a devastating fire swept through 2 bays of the manufacturing facility at White Road causing huge damage to stock, instruments, plant and work in progress. No one was injured, but work was disrupted for several weeks. Large sections of the factory had to be rebuilt.

1998:  The Dimension Data Take-over
In August 1998 Plessey was bought by Dimension Data and World-wide African Investment Holdings for R1.6Billion, they retained BSW Data, Plessey Solutions and Communications Systems. the remaining divisions were bought back by a combined management buyout supported by Rand Merchant Bank. The corporate name was changed to Tellumat Pty Ltd. Tellumat continues to manufacture Plessey products as before. Dimension Data markets the telecommunications-only products in Africa, and Tellumat market all Plessey products world-wide, excluding African telecommunications products.

For more information please go to the Tellumat web site




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Last revised: February 20, 2024