Conel Hugh O'Donel Alexander was born 1909 in Cork, Republic of Ireland. Awarded the IM title in 1950 and the IMC title in 1970 he was British Champion in 1938 and 1956. During the Second World War he worked at Bletchley Park with Harry Golombek deciphering German Enigma codes and then later for the Foreign Office. His best result was 2nd= at Hastings 1937-38 tied with Paul Keres after Samuel Reshevsky and ahead of Salomon Flohr and Reuben Fine. He held Mikhail Botvinnik (+1, -1) in the 1946 Anglo-Soviet Radio Match and represented England on 6 Olympiad teams. He was also an author of note.
He passed away in Cheltenham in 1974. (source : chessgames.com)
I have always wondered what those "C H O D" - letters stood for. I figured it was some kind of WWII code. Now you also can be a codebreaker in these few enigmaes.