Newnham College has revealed the identities of 77 ex-students who worked for British Intelligence Services as code breakers during the Second World War.

The codebreakers, whose secret work has been revealed for the first time in a college exhibition, worked at Bletchley Park as a part of a team that intercepted secret messages and broke the Nazi Enigma code.

Bletchley Park, a country estate in Buckinghamshire, was the centre of Allied code-breaking during the Second World War, and the workplace of Cambridge alum Alan Turing.

Many of the women involved had taken their secrets to the grave, with their involvement in wartime operations only being unearthed following a five-year research project by the college. The researchers also estimate a further 20 alumni could have been involved in secret operations whilst employed in innocuous government roles during wartime.

Dr Sally Waugh, one of the leading researchers on the project, stated that students would often be headhunted for work by “powerful women” in the college who were related to men working for Bletchley Park.

The commander of Bletchley Park, Alastair Denniston, had turned to Newhnam for skilled linguists, as modern languages were perceived as “a women’s subject” at the time. With German speakers in high demand to break codes, Newhnam became a target for intelligence recruiters.

Researchers found that many women in the Bletchley Park archives were listed as being “temporary civil servants”, and little was documented about their contributions to the war effort.

Speaking about her research efforts, Dr Waugh said: “The problem we had was, the whole point of Bletchley Park was that you couldn’t find out anything about it. And because they signed the Official Secrets Act, it was ingrained in most of the women not to speak about it.”

She also observed how many of those involved were willing to conceal their contribution at Bletchley Park, noting how when one of the Newnham codebreakers, Jane Monroe was asked what she did during the war, she would always state that she “made the tea”.