The secure voice communications machine that Alan Turing and Donald Bayley built at Hanslope Park was called Delilah.
Turing worked on the project after visiting Bell Labs in the United States, where he studied secure speech technology. At Hanslope Park in Buckinghamshire, he collaborated with Donald Bayley, a Royal Electrical and Mechanical Engineers officer and electronics specialist. Together they designed and constructed a portable system for enciphering speech.
Delilah was much smaller than the American SIGSALY system, which occupied a large installation and was used for highly secure transatlantic conversations. Delilah was intended for more portable, shorter-range applications, including telephone or radio links. Its design combined electronic speech processing with a cryptographic key system.
The machine successfully demonstrated secure voice transmission. Officials were reportedly shown the system by hearing a recording of a Winston Churchill speech encrypted and reproduced. However, Delilah was completed too late to see wartime operational use and was not adopted as a standard system.
The distractors belong to related but different stories: Colossus was associated with Lorenz-cipher codebreaking, Typex was a British cipher machine, and SIGSALY was the separate American secure-voice system.