The Telephone Manufacturing Co Ltd used the trademark Temco for their synchronous and other electric master clocks circa 1935.
Further information provided by courtesy of James Nye (using in part info from the EHG Technical Paper 43).
" The Telephone Manufacturing Company Limited (TMC) was formed in 1924. By 1929 it had absorbed New Systems Private Telephones Limited, which became a subsidiary company and was later renamed Telephone Rentals Limited. Around the same time TMC absorbed Prince's Electrical Clocks Limited. The re-engineered Princeps clock became what we refer to as the Princeps New System. Chronomatic was registered as a trade name in 1935 and frequently appears on the dials of clocks which were also rented out by Telephone Rentals Limited.
The mechanism was moved from its low position to the top of the case in the 1950s, and became known as the High Impulse Transmitter, continued in manufacture until the 1970s. Telephone Rentals also installed other manufacturer's equipment, and latterly traded under the name TR Time Services Limited, disappearing within Mercury Communications in April 1990. During its history, TR acquired Dictograph, another firm that specialised in rentals, mainly of Magneta M36/M37 master clocks.
Telephone Rentals and Dictograph had a deliberate policy of destroying equipment that came back from rental, I am told usually after two contracts - 30 years at most), and there are therefore far fewer surviving examples of what were once amongst the most commonly installed systems. For example, the production rate of Magneta clocks was nearly double the annual total of Gent's.
TMC had several locations, but one main works is at Park Hall in West Norwood, west of the cemetery. Robson Road runs down the side of the cemetery from Norwood High Street towards the works, and the staff going to work each day down Robson Road referred to it as 'walking the wall'. Several people who still live in West Norwood worked there or had relatives that did. "
A minor correction to the above has been offered by T.L., a retired TR Engineer, who informs me that after the movement was moved to the top of the case in the 50s the clock was known as the "High Movement Impulse Transmitter" rather than the High Impulse transmitter.
Colin Reynolds, formerly of Gents, has also written to tell me:
"Gent used to manufacture master clocks, time products and fire alarm products for telephone rentals and badge them with their logo.
I remember designing a fire alarm equipement for them. They rented out electrical equipement and supplied the service for its maintenance and at Gent we had engineers visit the factory for training."