Conel Hugh O'Donel Alexander, CMG, CBE (19 April 1909 – 15 February 1974), was an Irish-born British cryptanalyst, chess player, and chess writer. He worked on the German Enigma machine at Bletchley Park during World War II, and was later the head of the cryptanalysis division at GCHQ for over 20 years. In chess, he was twice British chess champion and earned the title of International Master. He was usually referred to as C.H.O'D. Alexander in print and Hugh in person.
Many knowledgeable chess people believe that Alexander had Grandmaster potential, had he been able to develop his chess abilities further. Many top players peak in their late twenties and early thirties, but for Alexander this stretch coincided with World War II, when high-level competitive opportunities were unavailable. After this, his professional responsibilities as a senior cryptanalyst limited his top-class appearances. He defeated Mikhail Botvinnik in one game of a team radio match against the Soviet Union in 1946, at a time when Botvinnik was likely the world's top player. Alexander made important theoretical contributions to the Dutch Defence and Petroff Defence. SOURCE: Wikipedia
Game Source: Modern Chess Miniatures, 1960, by Leonard Barden and Wolfgang Heidenfeld pp 16-17. Unattributed notes are by Heidenfeld, references to any games past 1960 are from MCO-15 pp 98-99.