Dilly Knox file photo [25537]

Dilly Knox

Given NameAlfred
Born23 Jul 1884
Died27 Feb 1943
CountryUnited Kingdom


ww2dbaseThe archetypical eccentric British boffin, Alfred Dillwyn "Dilly" Knox was educated at Summer Fields School, Eton College and King's College, Cambridge where he studied the classics. Knox was appointed a master at Cambridge in 1909 where he became an expert on ancient papyn, and during the Great War he was recruited as a codebreaker in Whitehall's Room 40 where he famously helped decrypt the Zimmermann Telegram that brought the United States into the war. Very often inspiration would come in a bath that he had found in an office at the end of a corridor; he thought best in hot water. On one occasion worried colleagues had to force open the door to check that he hadn't drowned. He was found to be engrossed in calculations. He also managed to conduct a romance with a fellow worker, Olive Roddam, a classicist from King College, Cambridge while employed at Room 40.

ww2dbaseDuring the inter-war years Knox worked for the Government Code and Cypher School (55 Broadway, St. James' Park, London) partly on Soviet encryptions, but also on devising ways of defeating the early versions of Enigma, which had been brought into use by Germany and Spain. Knox was 55 years old at the outbreak of World War Two and, during that summer, had been one of the hand-picked number of brilliant intellectuals, expert linguists, retired classics masters, crossword inclined W.R.N.S., and other young soldiers of high intellect recruited to work at the newly acquired top secret codebreaking establishment at Bletchley Park.

ww2dbaseFrom the start of the work at Bletchley there was a sense that his rigorous time-consuming methods were being superseded by developing technology. Nevertheless, he was a force to be reckoned with, on and off duty. Building on earlier research by Hugh Foss, another of Bletchley Park's great minds and an expert on Japanese encryption, Dilly Knox developed a system known as "rodding", a linguistic as opposed to mathematical way of breaking Enigma codes. This technique worked particularly well on the Enigma system used by the Italian Navy. He had a marked preference for working with young, attractive and tall women. The obvious reasons aside, there has been some suggestion that this was because he found that women like Mavis Lever had exactly the right mental approach towards the exhausting work. In 1941, aged 20, using Knox's "rodding" method, Miss Lever was responsible for cracking the Italian Enigma codes which led to the British naval victory at the Battle of Cape Matapan. Knox was fond of testing his female recruits to Bletchley with lateral teasers. "Which way round do the hands of a clock go?" was one. The answer it depends whether one is observing the clock or whether one is the clock itself. Such posers were intended as mental exercises to help when confronting intractable coding difficulties; to inculcate the habit of approaching insoluble problems from wholly unexpected angles.

ww2dbaseHis eccentric behaviour would show itself in other ways. He was noted for his endless capacity for writing rude memos about his superiors and his apparent ability to subsist entirely on chocolate and coffee. He was also a terrifying driver, especially along country lanes; given to reciting Milton, and gesticulating along with the verse, his hands off the steering wheel. At Bletchley Park, when deep in thought, he would occasionally try to refill his pipe with sandwiches, and was also, reputedly, incapable of finding the right door out of the room at the first attempt; seemingly heading at full tilt into store cupboards.

ww2dbaseKnox's important war work was cut short, however, when he fell ill with Lymphoma. When he became unable to travel to Bletchley Park, he continued his cryptographic work from his home in Hughenden, Buckinghamshire. He died on 27 February 1943. His team at Bletchley Park, nevertheless, continued to provide valuable intelligence and by the end of the war they had disseminated some 140,800 Abwehr decrypts including important intelligence vital for the D-Day operation.

Sinclair McKay, Bletchley Park - The Secret Archives (Aurum Press, 2016)

Last Major Revision: Mar 2016

Dilly Knox Timeline

23 Jul 1884 Dilly Knox was born in Britain.
27 Feb 1943 Dilly Knox passed away from lymphoma in Britain.

Did you enjoy this article or find this article helpful? If so, please consider supporting us on Patreon. Even $1 per month will go a long way! Thank you.

Share this article with your friends:


Stay updated with WW2DB:

 RSS Feeds

Posting Your Comments on this Topic

Your Name
Your Email
 Your email will not be published
Comment Type
Your Comments
Security Code



1. We hope that visitor conversations at WW2DB will be constructive and thought-provoking. Please refrain from using strong language. HTML tags are not allowed. Your IP address will be tracked even if you remain anonymous. WW2DB site administrators reserve the right to moderate, censor, and/or remove any comment. All comment submissions will become the property of WW2DB.

2. For inquiries about military records for members of the World War II armed forces, please see our FAQ.

Search WW2DB & Partner Sites
More on Dilly Knox
Event(s) Participated:
» Enigma Code Broken

Famous WW2 Quote
"Goddam it, you'll never get the Purple Heart hiding in a foxhole! Follow me!"

Captain Henry P. Jim Crowe, Guadalcanal, 13 Jan 1943

Support Us

Please consider supporting us on Patreon. Even $1 a month will go a long way. Thank you!

Or, please support us by purchasing some WW2DB merchandise at TeeSpring, Thank you!