By Noah | June 18, 2012
Awhile ago I posted an entry recommending a Nice Video about Colossus and Tommy Flowers. I have since been in touch with Capt. Jerry Roberts, who was one of the key members of the codebreaking team at Bletchley Park (B.P) during World War II. Capt. Roberts contacted me after I made my posting, and although he’s delighted to see the increasing recognition that’s coming to so much of the vital work done at B.P., he did have some concerns about details in the video.
In an e-mail to me, he made the following points (all quotations are directly from him…the “Testery“, mentioned in the quotes below, was the section of B.P. devoted to daily breaking of the message encipher on Tunny code, which was used by the German high command, including Adolph Hitler himself):
- “Colossus was built with one purpose only – to assist the Testery in speeding up one stage (breaking the chi wheel) of the breaking of Tunny, but the rest of the stages were still worked out by hand in the Testery by codebreakers and support staff. Without Bill Tutte breaking the Tunny-system, without the Testery daily breaking of Tunny, there would have been no need for Colossus at all.”
- The video compares the performance achieved using Colossus with the previous approach, which was to do the codebreaking entirely by hand. “They said [in the video] a message took 6 – 8 weeks to break the wheel patterns by hand; in fact we normally broke within 6 to 8 hours (within a shift); rarely, up to 16 hours might have been required. I know, I was a leading codebreaker doing this breaking all that time. Prof. Jack Copeland also quotes it as inside 8 hours, normally.”
- “From mid 1942 to mid 43 for the whole year, the Testery was breaking Tunny messages without any machine help (all by hand), included the messages relating to the Battle of Kursk – biggest tank Battle ever. Even when Colossus came later in spring 1944, still most work was done by hand in the Testery. The Testery broke 90% all the traffic handled on Tunny. The Newmanry (handled machinery – Robinsons and Colossuses) did 20 to 25% of the workload, and Testery did 75% at least. However, there is nothing about these inside information at B.P, as they are more keen to show off the machinery. “
By the way, Capt. Roberts remains very active in helping to promote recognition for all the good work done at Bletchley, and he is a terrific speaker. His belief (and the belief of many others) is that “Enigma decrypts helped Britain not to lose the War in 1941. Tunny decrypts helped shorten the European War by at least 2 years.”
Several years ago, before I realized we had mutual friends, I posted an entry recommending one of Capt. Roberts’ talks at UCL.
Note: this posting was updated on 27 June 2012 with minor corrections and annotations from Capt. Roberts, who was kind enough to review my original version.