Editing Ultra (cryptography) (section)

===1970s===
The 1973 public disclosure of Enigma decryption in the book ''Enigma'' by French intelligence officer [[Gustave Bertrand]]{{sfn|Bertrand|1973}} – which dealt mainly with the Polish and then Franco-Polish efforts before the [[Invasion of France]] and before the Ultra program{{sfn|Deutsch|1977|pp=16-17}} – generated pressure to discuss the rest of the Enigma–Ultra story.{{cn|date=May 2025}}

Since it was British and, later, American message-breaking which had been the most extensive, the importance of Enigma decrypts to the prosecution of the war remained unknown despite revelations by the Poles and the French of their early work on breaking the Enigma cipher. This work, which was carried out in the 1930s and continued into the early part of the war, was necessarily uninformed regarding further breakthroughs achieved by the Allies during the balance of the war.

The British ban was finally lifted in 1974, the year that a key participant on the distribution side of the Ultra project, [[F. W. Winterbotham]], published ''The Ultra Secret''.{{sfn |Winterbotham |1974a }} Winterbotham's book was written from memory and although officially allowed, there was no access to archives.{{sfn|Deutsch|1977|p=17}} Public discussion of Bletchley Park's work in the English speaking world finally became accepted, although some former staff considered themselves bound to silence forever.<ref>{{Citation |last=Withers-Green |first=Sheila |title=audiopause audio:<!--<<regularize this cite--> I made a promise that I wouldn't say anything |year=2010 |url=http://audioboo.fm/boos/176850-i-made-a-promise-that-i-wouldn-t-say-anything-sheila-withers-green-bpark2010?playlist_direction=forward |access-date=15 July 2011 |archive-url=https://web.archive.org/web/20111008045611/http://audioboo.fm/boos/176850-i-made-a-promise-that-i-wouldn-t-say-anything-sheila-withers-green-bpark2010?playlist_direction=forward |archive-date=8 October 2011 |url-status=live}}</ref>

Other books such as [[Anthony Cave Brown]]'s ''[[Bodyguard of Lies]]'' and [[William Stevenson (Canadian writer)|William Stevenson]]'s ''A Man called Intrepid'' were also being written at this time, and the military historian [[Harold C. Deutsch]] regards Winterbotham's revelations as only to have anticipated what were going to be a number of revelations.{{sfn|Deutsch|1977|p=28}}