D 3005
Issue 7, 14.2.66

Locks and Keys

1. General
This Instruction details the various locks and keys used in association with coin-collecting boxes, and indicates the arrangements to be made for their provision and use. Tp. S.I. G3 XV 17-21 refers.

2. Types of locks and keys
The locks and keys to be used in association with the mechanism and cash compartments are shown in Table 1.

Table 1

Type of
Container, Cash, No....  Lock Container, Cash, No....  Key Cash compartment Lock Cash compartment Key Mechanism compartment Lock Mechanism compartment Key
Public call offices Lock No. 15... (identified by code letters) Appropriate Key, Lock, No. 15... Lock No. 6M (identified by manufacturer’s name, suffix letter and serial number) Appropriate Key, Lock, No. 6M Box, CC., Parts
Lock No. 39...
(see pars. 3 and
Appropriate Key, Lock, No. 39...
coin-box installations
Not used Not used Lock No. 14A (or Lock No. 6M when Box, C.C., No. 705 fitted) Appropriate
Key, Lock,
No. 14 or No.
Box, C.C., Parts:
Lock No. 39... or Box, C.C., Parts: Lock No. 31 (see pars. 3 and 4)
Key, Lock, No.
39... or Key,
Lock, J


3. Locks

  1. Boxes, C.C., Parts: Locks No. 31 are gradually being replaced by Boxes, C.C., Parts: Locks No. 39... with the exception that, to facilitate maintenance, the former should always be fitted to coin-collecting boxes which are required to be permanently installed on-board ships. Retrospective action should only be taken when it is considered necessary in the interests of security.
  2. Boxes, C.C., Parts: Locks No. 39... are available in different combinations which are identified by suffix letters (e.g. Box, C.C., Parts: Lock No. 39BG) and each Maintenance Control area has been allocated a particular combination.
  3. If temporary shortage of any particular combination of Boxes, C.C., Parts: Locks No. 39... should occur, the Supplies Dept. have been instructed to supply Boxes, C.C., Parts: Locks No. 31 in lieu, if available.

4. When Boxes, C.C., Parts: Locks No. 39... should be used:-

  1. New work - When a coin-box is to be installed, a Box, C.C., Part: Lock No. 39... must be requisitioned and issued to the fitter with the other stores. The locks are supplied without keys because the maintenance officers will already have keys of the correct combination and the fitter should be loaned a key for the duration of the job from the Installation Control pool of keys [see par. 8(b)].
  2. Maintenance replacements - W hen a defective lock (whether of No. 31 or No. 39 pattern) requires maintenance replacement, a Box, C.C., Parts: Lock No. 39... should be obtained on maintenance exchange, except where the lock is required for a coin-collecting box permanently installed on-board a ship (see also par. 7).
  3. Special cases - Because of the possibility of a Box, C.C., Parts: Lock No. 31 being issued in lieu of a Box, C.C., Parts: Lock No. 39... during any period of shortage of the latter type [see par. 3(c)], requisitions for Boxes, C.C., Parts: Locks No. 39... that are intended for use at public call offices or on Boxes, C.C., No. 705 fitted on subscribers’ installations should be endorsed ‘Box, C.C., Parts: Lock No. 31 not acceptable’.

5. Precautions when fitting locks
When fitting locks it is important that the lock adjustments detailed in D 3004 for pay-on-answer coin boxes and D 3003 for pre-pay-on-answer coin boxes are carried out to ensure that a tight fit consistent with ease of operation of the lock is obtained.

6. Requisitioning instructions
T.M.s have been advised of the Punched Card Unit numerical codes of the particular combinations of locks and keys used in their Areas and these codes must be used when requisitioning. Requisitions for new and replacement keys must be signed by the Area Engr., who should satisfy himself of the need for the demand.

7. Disposal of recovered locks and keys

  1. Locks - Return serviceable locks to the Supplies Dept. clearly labelled ‘Fit for reissue’. Defective locks must be destroyed in the presence of the local supervising officer, who should then list the locks on a form A 283 and certify that the locks have been destroyed. The form A 283 should be forwarded to the Clerical Divn. (Stores Duty). NOTE: To destroy the locks, it is essential that the levers are thoroughly distorted.
  2. Keys - When keys are returned to the Supplies Dept. they must be dispatched in accordance with STORES, Workmen’s Procedure, P 0011. Label serviceable keys ‘Fit for reissue’.

8. Care of keys
It is very important that the strictest control be exercised over the issue of keys, their location, and their subsequent disposal. To facilitate this control, after issue, it is essential that keys should not be taken out of the Area in which they were issued and, where reasonably possible, an engineering officer holding keys permanently [see (b)] should return them to his supervising officer before proceeding on annual leave for a period of over four days, or in the event of protracted sick leave; it will also be necessary for an officer to hand over his Key, Lock, No. 39... before proceeding on transfer to another Maintenance Control area.

Officers to whom keys may be issued
Engineering officers who must have access to coin-collecting box mechanisms have to hold both a Key, Lock, J and a Key, Lock, No. 39... of the combination proper to the Maintenance Control area in which they work. As far as practicable, only those officers who, in the course of their normal duties, require daily access to coin collecting-box mechanisms should hold keys permanently. Any officer who requires the use of a key at infrequent intervals only should obtain one from a central point, e.g. the Maintenance Control or an attended exchange to which he should return the key when he has finished with it. Spare keys held for this purpose should be kept in safe custody when not in use. Fitters who work in more than one Maintenance Control area will require a Key, Lock, No. 39... of each code concerned. The correct key should be issued with the Advice Note and returned on completion of the job. The importance of restricting issues of these keys cannot be too strongly emphasized.

Record of keys held in each Area
A complete and accurate record of all coin-collecting-box mechanism compartment keys held in each Area should be
prepared and maintained by the Clerical Divn. (Stores Duty). The H.C.O. should ensure that the record is reviewed each year by sending each local supervising officer concerned a list of names of those officers under his control who hold keys and the types and number of keys held. The supervising officer should check that the keys are still held and certify that

  1. each key is still in the possession of the officer named, and
  2. it is still necessary for each key to be retained. (Dispose of keys no longer required in accordance with par. 7.)

Lost keys
The loss of any key should be thoroughly investigated by the supervising officer.

Key chains
A Key Guard (SP66), which consists of a 1.25 in. split ring on a 16 in. chain with a leather tab for attachment to a trousers button, may be obtained as necessary from the Clerical Divn. (Stationery Duty) for officers who normally are required to carry several keys.


9. Permanent locks
Arrangements for the provision and fitting of the permanent Lock No. GM for the cash compartment will be made by the Clerical Divn. When a new coin-collecting box is to be installed, the Engineering Divn. will advise the Clerical Divn. in reasonable time, so that arrangements may be made for the permanent Lock No. 6M to be fitted as soon as possible after the completion of the installation.

10. Temporary locks for use by engineering staff
It may sometimes be convenient, e.g. when a new installation is fitted or a fault is cleared, to arrange locally for an engineering officer to secure the cash compartment by means of a suitable lock of the No. 6 type. A small stock of these locks (and in addition in some Areas, a stock of earlier-pattern lock known as a Lock No. 2) is held locally by the engineering staff for this purpose. The permanent Lock No. 6M will be placed in position by the collector as soon as convenient, and the temporary lock will be returned to the Engineering Divn. at the earliest moment. Keys for these temporary locks should be held by the engineering staff, and by the Clerical Divn., a key being sent by the latter to the Head Postmaster responsible for normal clearing of any box to which a temporary lock has been fitted.

Standard items used for this purpose are:-

  1. Locks No. 2 and Key, Lock, F
  2. Locks No. 6C and appropriate keys
  3. Locks No. 6M and appropriate keys

Further provision of items (a) and (b) will not be made and, when it is required to augment the present stock or to replace a faulty item, obtain Locks No. 6M and appropriate keys from the Chief Clerk (Clerical Divn.) to whom faulty items should be returned.

11. Containers, Cash, No....
The arrangements for the initial fitting of a Lock No. 15... used with this container are described in D 3902, which describes the procedure for dealing with new locks found to be faulty at the time of fitting.

Locks becoming faulty in service should, as far as the engineering staff is concerned, be treated as follows:- The container (complete) on which the lock is faulty, and the appropriate key, will be handed to the Engineering Divn. by the Head Postmaster. If the difficulty is due to the lid having been interchanged, so that the lock-bolt will not slide beneath the latching plate of its new container, correct this as described in D 3902. If the lock itself is faulty, remove it and hand it to the Postmaster’s representative; in due course a new lock will be supplied which should be fitted as described in D 3902.

Keys for these locks, with the exception of Keys, Lock, No. 15 ENG whether for new work or replacement of faulty items, will be obtained by the Clerical Divn. or Head Postmaster only, and will not be held by engineering officers.

To enable engineering officers to test the functioning of containers cash, Locks, No. 15 ENG and Keys, Lock, No. 15 ENG are available. These locks have the same dimensions as other Locks No. 15... but are only used by engineering staff. The Lock, No.15 ENG supersedes the Lock No. 19 which was a dummy lock operated by a screwdriver (see A 5902).


12. Supply of locks
When an Advice Note is issued for the provision of a subscriber’s circuit with a coin box, the Clerical Divn. will issue a Lock No. 14A or Lock No. 6M, as appropriate, with the Advice Note. The Installation Control will inform the Clerical Divn. sufficiently early to ensure that the appropriate key is in the subscriber’s possession before the Advice Note is issued to the fitter (see WORKS, Execution, C 0016). Subscribers should not be provided with a key to the mechanism compartment. The fitter should fix the lock to the cash compartment with the securing screws provided with the coin box. When the installation is ready for service the subscriber should be requested to lock the cash compartment. The fitter should check that the cash compartment is locked before placing the installation in service.

13. Replacement of cash compartment lock
When it is necessary to change a cash compartment lock, ask the Clerical Divn. to provide a Lock No. 14A or Lock No. GM, as appropriate, and dispatch the key to the subscriber. At the same time, advise the Clerical Divn. of the date on which it will be convenient to make the change, so that the items to be replaced will be available in time. When the lock has been changed, request the subscriber to lock the cash compartment.

Return the recovered lock to the Clerical Divn. immediately and ask the subscriber to return the old key to the T.M. (Clerical Divn.).


14. Access to cash compartment
When it is necessary, for maintenance purposes, to gain access to the cash compartment of a coin box, make arrangements for a collector (or the subscriber, in the case of a subscriber’s circuit with coin box), to clear it at the time and, subsequently, to re-lock it.

15. Forcible removal of locks
Due to keys being lost or lock mechanisms becoming jammed it is sometimes necessary to use force to remove the locks fitted to coin-collecting boxes. The various methods to be employed to ensure that a minimum of damage is sustained by the coin box consistent with reasonable labour charges are detailed in pars. 16 - 20. When a lock is to be removed from a cash compartment the collector, if a public call office, or the subscriber, if a subscriber’s installation, must be present to recover the cash. When coin boxes or coin-box parts are to be returned to Supplies Dept., the locks must first be removed.

16. Locks, No. 14 and No. 14A
These locks are of the cylinder type and it is necessary to sever the pins that lock the cylinder to the fixed barrel. To sever the pins, drill a hole 5/16 in. diameter and approximately 7/8 in. deep in that part of the lock barrel that has the lock type number stamped on it, in a position in line with the cylinder key slot and overlapping the cylinder by approximately 1/16 in. To drill the hole use a carpenters brace, do not use power tools as their use for this particular task may be dangerous. When the hole has been drilled, rotate the cylinder by means of a screwdriver or similar tool inserted in the key slot and release the lock.

17. Locks No. 6M fitted to Boxes, C.C., No. 705
Replace the cash compartment complete with lock, by the methods described in D 5010, and remove it to the maintenance centre, linesman’s headquarters or wherever suitable facilities are available to perform the following work.

Remove the cover locking studs, the two angled locking plates and the two 4BA screws from the upper surface of the cash compartment. Remove the two hexagonal rods from the lower part of the cash compartment using a Spanner, Box, No. 4. To remove the rods it is necessary to prevent the two nuts, located in recesses at either side of the steel lining, from rotating. Withdraw the lining and Front No. 10 from the cash compartment casting. Destroy the lock by drilling a hole 3/8 in. diameter and approximately 5/8 in. deep through the lining and into the lock mechanism in a position 1.1 in. from the inside face of the Front No. 10 and 2.6 in. from the left-hand vertical of the lining when viewed from the rear. Do not make attempts to drill through the lock from the outside of the lock housing or a hole deeper than that recommended as the lock outer casing is of hardened steel and damage to drills may result. Remove the faceplate of the Front No. 10 and dispose of it locally to the best advantage. Dispose of the lining, lock and remainder of the front as rubbish and not as scrap metal. The local supervising officer should issue a destruction certificate (see par. 21) for the lock to the Chief Clerk (Clerical Divn.). The remainder of the cash compartment should be rebuilt by fitting a new lining (N.R.B. Part No. 1/DGU/65 item code No. 460044) and Front No. 10. Part No. 1/DGU/65 should only be requisitioned when required and not held in Section or Normal Stocks.

18. Locks No. 6M fitted to Boxes, C.C., No. 14D and No. 16B
When forcible removal of a Lock No. 6M fitted to a pre-pay-on-answer coin box is necessary, refer the case to the Clerical Divn. who will obtain the services of a locksmith.

19. Locks No. 15...
Should the lock fitted to a cash container become jammed, drill off the riveted ends of the lock mounting studs and prise the lid off. Remove the lock and obtain a replacement, see par. 11. Obtain a new lid on maintenance exchange.

20. Mechanism compartment locks
Should the lock fitted to the cover of a Boxes, C.C., No. 705 become jammed, remove it by the method described in D 5010, with all other types of coin box it is necessary to lever off the front. Lever off Fronts No. 11 from the top; the lever being inserted between the lip in the case and the front and then the lever pulled forward. Lever off other types of fronts from the bottom.

21. Destruction certificates
Destruction certificates for locks should be made out locally in the following form and signed by an officer of rank not lower than Inspector.

The Chief Clerk
This is to certify that the Lock No. 6M removed from (insert exchange and number of coin box) has been destroyed in my presence, and disposed of, in accordance with El. TELEPHONES, Call Offices, D 3005.

Duty Code

22. Destruction of locks and keys
Defective Locks Nos. GM, 14... and 15... and Keys, Lock, Nos. 6M, 14... and 15... must not be returned to the Supplies Dept. and the Eng. Divn. will therefore at the request of the Clerical Divn. destroy faulty items and issue destruction certificates similar to that described in par. 21. To effectively destroy locks and keys it is essential that the levers, tumblers or key steps are mutilated so that their dimensions cannot be used to construct keys. Dispose of keys and lock levers as follows. Dispose of all other parts as scrap metal.

To destroy a Lock No. 6M or No. 15... dismantle the lock and remove the levers. Dispose of the levers in a solid-fuel furnace, if available, or after thoroughly mutilating them, dispose of them as rubbish.

To destroy a Lock No. 14... dismantle the lock and using a hammer and suitable drift, drive the cylinder out of the barrel from the rear. Alternatively, clamp the lock in a vice and drill a hole in the barrel as described in par. 16.

To destroy keys dispose of them in a solid-fuel furnace or clamp them in a vice and mutilate the stepped part, using a hammer and cold chisel, then dispose of them as rubbish.

Note:-  The later armoured type 705 was fitted with a Lock No. 42 on the mechanism cover.

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Last revised: February 10, 2021