[1] While women were overwhelmingly under-represented in high-level work such as cryptanalysis, they were employed in large numbers in other important areas, including as operators of cryptographic and communications machinery, translators of Axis documents, traffic analysts, clerical workers, and more.

It housed the Government Code and Cypher School (GC&CS), which regularly penetrated the secret communications of the Axis Powers – most importantly the German Enigma and Lorenz ciphers.

According to Sir Harry Hinsley, the "Ultra" intelligence produced at Bletchley Park shortened the war by approximately two years.

[1][2][5][6] In 1944, when the tensions in Europe and Asia were becoming apparent, the Chief of MI6, Admiral Hugh Sinclair, ordered GC&CS to begin preparing for a war-footing and to expand its staff numbers.

[2] Women were first brought into Bletchley Park after being approached at university or because of trusted family connections; debutantes especially were prized, as they were considered the most trustworthy due to their upper class backgrounds.

Winners were approached by the military and some were recruited to work at Bletchley Park, as these individuals were thought to have strong lateral thinking skills, important for codebreaking.

[10] The majority of these women came from middle-class backgrounds[11] and some held degrees in mathematics, physics and engineering; they were given entry into STEM programs due to the lack of men, who had been sent to war.

Women held numerous roles at Bletchley Park, ranging from administrators, index card compilers and dispatch riders, to a very few as code-breaking specialists.

[20] At the outbreak of the war Dilly Knox was the GC&CS's chief cryptanalyst and, as such, took a leading role in the work on the various Enigma networks.

[21][22] During a September 1941 morale-boosting visit, Winston Churchill reportedly remarked to head of GC&CS Alastair Denniston: "I told you to leave no stone unturned to get staff, but I had no idea you had taken me so literally.

Initially employed to check the personal columns of The Times for coded spy messages,[27] in 1940 she was recruited to work as a codebreaker at Bletchley Park.

[28][29][30] According to The Daily Telegraph, she became so familiar with the styles of individual enemy operators that she could determine that two of them had a girlfriend called Rosa and this insight allowed her to develop a successful technique.

"[34] Jean Valentine was an operator of the bombe decryption device in Hut 11 at Bletchley Park in England, designed by Alan Turing and others during World War II.

[47] On 24 June 2012, Jean Valentine spoke on her wartime experiences at Bletchley Park and elsewhere as part of a Turing's Worlds event to celebrate the centenary of the birth of Alan Turing, organized by the Department for Continuing Education's Rewley House at Oxford University in cooperation with the British Society for the History of Mathematics (BSHM).

Though she did not personally seek the spotlight, her important role in the Enigma project that decrypted Nazi Germany's secret communications earned her awards and citations, such as appointment as a Member of the Order of the British Empire (MBE), in 1946.

Due to the secrecy of Bletchley Park and the United Kingdom's Thirty-year rule, it wasn't until the 1974 publishing of The Ultra Secret by former RAF officer F. W. Winterbotham (who supervised the distribution of Ultra intelligence) that the wartime role of Bletchley Park began to be discussed, and only in 2009 did the British government award honours to its personnel.