Martyn Rowlands designed the Trimphone in 1964. Anthony Wedgewood Benn, then Postmaster General, presented the first one, the ten millionth telephone, to a subscriber in Hampstead in May 1965. The Post Office was on the brink of a new era. In the same year, Labour Prime Minister, Harold Wilson opened the Post Office Tower in London.
The Deltaphone as STC the manufacturer of the Trimphone called it, won a Council for Industrial Design (COID) award in 1966. Designer Martyn Rowlands made a model of a push button version as well as a dial version. The COID praised the lightness of the design, which was around half that of existing telephones. Rowlands was a freelance designer with considerable experience with plastic products. He had already two COID awards under his belt when he designed the Trimphone.
However, the new technology proved difficult to master. It took years to get to the definitive version, the 722, which was not delivered to customers until 1971.
Inspiration and early development
The inspiration for the Trimphone was the Bell Princess phone from the USA from 1959. Executives at the GPO thought a similar phone would be popular in the UK. Their original brief was for a small, light bedroom phone, with a light to illuminate it. The GPO management had discussions with manufacturers, including GEC and the Standard Telephone Company (STC), as early as 1960.
Martyn Rowlands' design for STC was eventually chosen in 1964 and the GPO placed an initial order for 10,000 units.
TRIMphone stands for Tone Ringer Illuminated Model. Its sleek, modern design placed the handset N-S instead of E-W. It suited the GPO's aspiration to be modern.
The Trimphone was the first attempt to design a modern electronic phone. An electronic warbler replaced the traditional bell. Engineers carefully tuned the warbler so it was not confused with birdsong. However, starlings quickly learnt to imitate the Trimphone's ring. The dial glowed in the dark, thanks to low dose radioactivity and caused controversy when BT tried to dispose of old Trimphones in the 1980s. The phone had a long lead so you could move around the room whilst having a conversation, making it the ideal sixties' party phone.
The microphone for the Trimphone is not where you would expect. It is near the earpiece and linked to the mouthpiece via acoustic coupling. Engineers spent a considerable amount of effort designing an internal acoustic horn to couple the microphone opening on the handset with the actual microphone, so it was possible to mute the phone by covering the microphone opening.
You could chose from three colour schemes, two-tone blue, grey and green or grey and white. The Trimphone was not loud and brash like some sixties products, but more subtle and sophisticated. These phones were more about understated good design than fun and fashion.
The COID liked the Trimphone, although Fiona MacCarthy writing for the Guardian in 1966 thought it was designed for obsolescence. History, of course, proved her wrong, but that may have been down to the GPO's monopoly rather than the timelessness of the original design.
In the commercial world there are always huge pressures to get a product to market quickly, but the GPO, the UK's only telephone service provider, took its time. The limited trial roll out of the Trimphone began in the London North West Area in November 1965. In Summer 1966, the GPO extended the trial to London North, Northern Ireland and Wales.
The field trials did not go well. In early trials on shared service lines or party lines, it was possible for the other party to hear dialling by his neighbour, leading to calls being overheard. Also the quality of the microphone in the handset deteriorated quickly and needed replacing, this problem was later solved by fitting a Regulator 7A across the microphone terminals of the transmission board.
As a luxury product, customers had to pay more for the Trimphone. At the time when only around 20% of the population had a phone of any kind, they were not common. Initially you had to pay an extra £1 installation change and extra rental of 7/6d per quarter. If you already had a phone, the GPO charged 30s to change your existing phone; hardly an incentive to upgrade.
After several field trials, the GPO made the Trimphone available to all customers in February 1968. They demonstrated the new phone at the 1968 Daily Mail Ideal Home Exhibition and signed up many new and eager customers at the event. By June 1968, they had installed 36,000 Trimphones.
One fault that was never fixed was a direct result of the design brief for a small, light phone; the Trimphone could move about when you dialled. STC developed a low torque dial to fix this issue, but it was never accepted by the GPO.
The Trimphone with its extra rental charges was never going to have a huge following and most telephone customers opted for the standard 706 or 746 phones. The Trimphone though gained status as a luxury item in the 70s and is now a retro classic. A Trimphone is an important prop for estate agent, Laurence Moss, in the 1977 parody of middle class life in Mike Leigh's play, Abigail's Party.
Early Trimphones often had the classic lettered dial, making them highly prized by collectors. All figure numbering, as the GPO called it, did not come in until the end of the 1960s and lettered telephone exchanges were the norm in the 60s.
The lettered dial has a transparent circular disk over the telephone number, but disks from newer phones do not fit the transparent dial, which is subtly different.
All GPO phones had model numbers normally stamped on the base of the phone. The original Trimphone was Telephone 712.
The Trimphone went through several revisions before the final version, the 2/722 was offered in 1971. Trimphone model numbers were:
- Telephone 712 Mk1 - introduced May 1964
- Telephone 712 Mk2 - introduced March 1996
- Telephone 722 - introduced June 1966
- Telephone 1/722 - introduced November 1969
- Telephone 2/722 - introduced June 1971
- Telephone 766 - Push Button Trimphone, 1976
- Telephone 786 - MF (touch tone) dialling version of PB Trimphone, 1979
- Telephone 8722 - PST (Plug and socket) version of the 2/722, 1982
- Telephone 8766 - PST (Plug and socket) version of the 766
- Telephone 8786 - PST (Plug and socket) version of the 786
The letters L and F after the model number indicate a lettered (L) or figured (F) dial. So Telephone 1/722L was a lettered dial version of the 1/722. The vast majority of phones for sale on eBay are of the 2/722 type.
The field trial phones can be identified by additional numbers on the base. To read more about the field trial phones, how to identify them and what the extra number on the base mean see: Field Trial Trimphone
What to look out for
Trimphones are regularly for sale on eBay. Look for ones in good condition. Avoid heavily faded examples. You can usually tell if a Trimphone has faded badly because the part of the phone hidden by the handset will appear to be a different shade.
Most have been rewired for modern use, but you can usually get a bargain if a phone has not been rewired and is in good cosmetic condition.
There are a number of reproduction Trimphones on the market made by 'Wild and Wolf' and by Steepletone. The seller should make it clear that the phone is a reproduction, but if not, look out for unusual colours. Wild and Wolf phones have push button dials, but arranged in a ring, like a dial phone. Steepletone phones have a standard type dial.
If you want to buy a reproduction Trimphone, the 'Wild and Wolf' Trimphones are pretty good copies of the original. Steepletone Trimphones, in my opinion, are less so.
What to pay
You should be able to get a good 2/722 phone with a standard numbered dial for around £20. Exceptional examples will sell for more. Phoenixphones are worth more, ranging from £60 to £100.
The Push button Trimphone took the Trimphone concept a stage further in the 70s.
See www.britishtelephones.com/t712.htm for more information about the Trimphone.
For more articles about the Trimphone see:
- www.phone-pages.org.uk/trim.htm - a short history
- Wikipedia - the Trimphone
- www.samhallas.co.uk/collection/bits_trimphone.htm - How to disassemble a Trimphone
- telephonesuk.co.uk/phones_1960-80.htm - Trimphone pictures
By Steven Braggs, April 2012, corrections June 2012
Retrowow - Telephones
The online guide to retro telephones