Wrens operating Bombe machines (Larissa, Athens and Corinth) in the Greece Bombe Bay at Eastcote outstation.
Bombe machines tested possible Enigma settings much faster than humans. The Bombe was developed by Codebreakers Alan Turing and Gordon Welchman, and they were operated mainly by women from the Women’s Royal Naval Service (WRNS). Most of the Bombes were installed at outstations for security reasons and by the end of the war there were over 200 operational in the UK.