"The Bletchley Girls" from 'The Lady'
http://www.lady.co.uk/people/8425-the-real-bletchley-girls .
..by 1941 the cerebral origins of Bletchley Park had given way to an industrial scale code-breaking factory. A clutch of ‘professor-type’ cryptanalysts increasingly relied on a predominantly young female workforce to ensure the Allies stayed one step ahead of the enemy. At the peak of the war, women outnumbered men at Bletchley by three to one.share