The General Post Office (GPO) of the United Kingdom carried the sole responsibility for providing telecommunication services across the country with the exception of Hull. The GPO issued a range of telephone instruments to telephone service subscribers that were matched in function and performance to its telephone exchanges.
General history
Until October 1969, the GPO had a monopoly on the provision of all telephone lines and telephones within the UK, other than in Kingston upon Hull, which for historical reasons was unique in maintaining its own municipal telephone service. From the 1st of October 1969, the Post Office Corporation replaced the General Post Office with ownership of the former GPO business. Customers of the PO (known internally as "subs", short for 'subscribers') did not own their telephones. They were instead rented from the GPO, together with the house wiring and the wiring connecting the house to the local network at a connection point known as a DP (distribution point), which was generally located at the top of a nearby telegraph pole. During the early days of telephones, in the UK, a variety of instruments were produced, in low volume, often combining new and emerging technologies with the traditional skills of the wood joiner and cabinetmaker. They were simply known as Type 1, 2, 3 etc. These were often used on simple, internal links, sometimes taking the place of the 'speaking tube' in large houses. These instruments had no dials, and signalling consisted of a hand-cranked magneto generator. Often the bell at the other end would just be 'tinkled' by simply rattling the switch hooks up and down.←From these developed the first, serious, GPO instruments, the 100 series. This comprised the Type 121, a wall phone, and the Type 150, a desk phone.
Types 121 and 150
Both were based around the same handmade, wooden case, containing the telephone circuit and bell. The Type 121 had the transmitter mouthpiece screwed onto the front of the box and the switch hook, holding the receiver, protruding from the left hand side. Below the mouthpiece was a dial-mount, which either contained a dial (F or L - Figures only or with Letters - from about 1926) or a blanking plate (CB). This made it a true, one-piece telephone which was available either 'stand alone', mounted on a handsome, wooden, back-board, with integral writing desk or, as a Tele. 123, combined with the original, Button A & B coin-box.
The Type 150 'candlestick' two-piece telephone is now a collectible item. The bell receiver was originally coated in a black vulcanised rubber (Vulcanite) and the remaining brass work had a black oxide finish (In the photo the original black finish has been stripped to reveal the brass; the dial is also later, the original number 10 dial would also have been finished in black oxide on copper.) The L denotes an alphanumeric (rather than number only) dial plate. The dial uses a slipping cam Rotary dial - distinct from the CB (central battery) version - which was without any dial and relied entirely upon connection via the operator. The transmitter (microphone) was of a very poor, carbon granule construction, which absorbed moisture and required regular replacement. However, the low cost ensured that this transmitter would continue to be used for many years to come. In contrast, the twin coil and diaphragm receiver was of very good quality, indeed.
The Type 150, like its successor the Type 162, was actually only the 'front end' of the telephone. Containing only the transmitter, receiver and switch hook assembly; the entire electrical telephone circuitry was contained within an accompanying magneto bell set. This was initially the wooden cased version shown or the later, compact, Bakelite, Bell set 25.
Type 162 & 232 The 162 was originally launched in 1929 as the last of the 100 series. Once its potential was realised it was quickly promoted to a Type number of its own, becoming in 1934 (with some internal modifications) the 232 and staying in production until 1957. The Tele. 162 Handset Micro Telephone, was the first UK phone to incorporate the transmitter and receiver into a single unit, 'The Handset', which had not been used on telephones in the UK since the very early metal and wood cased models, and the BPO preference for a separate transmitter and Bell receiver, as on the Tele. 150 and Tele. 121. It was designed as a very lightweight domestic phone, which could be carried around whilst in use, by hooking the fingers under the switch-hook cradle. For this purpose it could be ordered with an extra long instrument cord at additional cost. It was even with a blanking plate instead of the dial. Like the Tele. 150, it required a Bellset 25 to complete its electrical circuitry and to provide bells. This could be either screwed directly under the telephone or mounted separately in another location. The Tele. 232 came out of the box fitted with a base plate containing a drawer, holding a personal directory card. The telephone could then be screwed directly onto the matching Bell set 26, making a true, but very heavy, telephone set, or screwed down onto the desk of a CCB (coin collecting box), in a Public Telephone Kiosk. In this form it was fitted with a modified dial, a more durable handset cord, and was re-numbered as the Tele. 242. There was one other variant. With modified internals and designed purely to be used in combination with a Bellset 39a or 44, this was the Tele. 248 in the guise of the Extension Plans 5 & 7. This type of telephone is often featured in British made period television dramas. Curiously, the telephone often rings despite not being fitted with any bell unit.
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