The Female Codebreakers Who Helped Win WWII
Bletchley Park's codebreaking is usually told as Alan Turing's story. By January 1945, nearly 10,000 people worked at Bletchley Park and its outstations, and about 75% of them were women — Wrens posted in from the Women's Royal Naval Service, women picked for foreign languages, and mathematics graduates recruited straight from Cambridge women's colleges like Newnham and Girton.
This video follows what they actually did: Joan Clarke's path from a Cambridge double first Cambridge would not award her, to deputy head of Hut 8 in 1944, developing Banburismus alongside Alan Turing; Mavis Lever (later Batey) and Margaret Rock's March 1941 break of the Italian navy's Enigma variant, which fed the intelligence behind the Royal Navy's victory at the Battle of Cape Matapan; the nearly 2,000 operators, the great majority Wrens, who ran about 200 Bombe machines in round-the-clock eight-hour shifts; and the 273 women who operated ten Colossus machines against the German Lorenz cipher, billeted at Woburn Abbey.
It then asks why this is remembered as a men's story: how women's analytical work was logged under lower-ranked job titles that left a thinner paper trail, and how the Official Secrets Act kept everyone silent for nearly thirty years until F. W. Winterbotham's 1974 book The Ultra Secret broke the silence — with the full technical record of the Lorenz attack not declassified until 2000. The video closes on how recognition has built since the Bletchley Park Trust's museum opened in 1993, up to Sir Dermot Turing's 2025 book Misread Signals and the public events discussing it into 2026.
Every figure is on screen with its source and date.
In these topics
Tags
Chapters
Sources and credits
Photo credits (Wikimedia Commons)
- Wren operating a Colossus-type codebreaking machine, Bletchley Park, WWII (identified elsewhere as Dorothy Du Boisson): Unknown authorUnknown author, Public domain - https://commons.wikimedia.org/wiki/File%3ADorothy_Du_Boisson.jpg
- Wartime photograph of a Bombe machine at Bletchley Park: Unknown authorUnknown author, Public domain - https://commons.wikimedia.org/wiki/File%3AWartime_picture_of_a_Bletchley_Park_Bombe.jpg
- Wartime photograph of Colossus 10 in Block H, Bletchley Park: Good, Jack; Michie, Donald; Timms, Geoffrey (1945), General Report on Tunny: With Emphasis on Statistical Methods, UK Public Record Office HW 25/4 and HW 25/5, Public domain - https://commons.wikimedia.org/wiki/File%3AWartime_photo_of_Colossus_10.png
- Surviving Colossus machine section, National Cryptologic Museum (presented by GCHQ to NSA, 1986): Daderot, CC0 - https://commons.wikimedia.org/wiki/File%3ACOLOSSUS%2C_part_of_the_machine%2C_presented_by_Director_GCHQ_to_Director_NSA_in_1986_-_National_Cryptologic_Museum_-_DSC07890.JPG
- Aerial photograph of the Battle of Cape Matapan, 27 March 1941: Wallington, A (Mid), Public domain - https://commons.wikimedia.org/wiki/File%3ABattle_of_Matapan._27_March_1941%2C_Aerial_Photograph._A9801.jpg
- Girton College, Cambridge - one of the women's colleges that supplied mathematics-graduate recruits to Bletchley Park: Adam Cuerden, Public domain - https://commons.wikimedia.org/wiki/File%3AGirton_College%2C_Cambridge%2C_England%2C_1890s.jpg
- Woburn Abbey, Bedfordshire - housed Colossus operators during the war: unknown, Public domain - https://commons.wikimedia.org/wiki/File%3AWoburn_Abbey.jpg
- 1945 photograph of the punched-card Central Index room, Bletchley Park: Good, Jack; Michie, Donald; Timms, Geoffrey (1945), General Report on Tunny: With Emphasis on Statistical Methods, UK Public Record Office HW 25/4 and HW 25/5, Public domain - https://commons.wikimedia.org/wiki/File%3ABletchley_Park_1945_photo_of_card_index.jpg
Primary sources
- Wikipedia, 'Mavis Batey' - Mavis Lever's recruitment, the March 1941 break, Cape Matapan.
- Wikipedia, 'F. W. Winterbotham' - The Ultra Secret, 1974, and the decision not to prosecute.
- Google Arts & Culture, 'The women of Bletchley Park' (a Bletchley Park Trust exhibit) - nearly 10,000 staff / 75% women by January 1945.
- Wikipedia, 'Colossus computer' - the 1975/1983/2000 declassification timeline.
- Vincent P. O'Hara, 'Struggle for the Middle Sea: The Great Navies at War in the Mediterranean Theater, 1940-1945', Naval Institute Press, 2009 - 'Italy's greatest defeat at sea.'
- British Computer Society events calendar, Kellogg College Oxford event listing, and Forces News, 'Female WWII codebreakers gather for book launch' - Sir Dermot Turing's 2025 book and 2026 events.
Not regulated financial advice.