GPO Telephones

The General Post Office (GPO) of the United Kingdom carried also the sole responsibility for providing telecommunication services across the country. The GPO issued a range of telephone instruments to telephone service subscribers that were matched in function and performance to its telephone exchanges.

Until 1982 the GPO had a monopoly on the provision of all telephones within the UK, other than in Kingston upon Hull, and so the range was limited. Customers (known within the GPO as "subs", being short for 'subscribers') did not buy their telephones, they were 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). The majority of DPs were (and still are) at the top of what are still known in the UK as telegraph poles.

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 instrument 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 a wall phone, the Tele. 121 and a desk phone, the Tele 150.

Both were based around the same handmade, wooden case, containing the telephone circuit and bell, but unlike the bellset, shown with the Tele 150, below, the Tele 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(L) 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 100 series, 'candlestick' two-piece telephone is now a collectible item. This one is a Tele. 150L circa 1929 and is a poor example since the original black finish has been stripped to reveal the brass. The bell receiver was originally coated in a black vulcanised rubber (Vulcanite) and the remaining brass work had a black oxide finish. 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, as 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. The low cost, however, 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 Tele. 150, like its successor the Tele. 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.

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Wikipedia