(1) Enigma was going well by this stage, but intelligence realised there must be another system when a stray teleprinter message was picked up by a listening post in Kent.

(2) The invention of the teletypewriter and its development of the teleprinter , linked to the telegraph system, added a further dimension to communications.

(3) The ideal arrangement is to have a teleprinter communicating between the two rooms.

(4) There were noisy typewriters and even noisier teleprinters , to say nothing of piles of typewritten sheets of paper.

(5) Other developments included automatic teleprinters which could transmit messages at a rate of 100 words a minute, and facsimile facilities which could transmit war photographers' prints halfway round the world in seven minutes.