Desmond Dillon attended Repton School and in 1939 passed the examination to become a naval cadet and joined the Royal Marines. In a long career in the Marines, he reached the rank of major. Dillon was awarded the Distinguished Service Cross (DSC) in 1952 and in 1971 was appointed a bodyguard to HM Queen Elizabeth II, a post he held until his death in 1988. His nephew Roger was appointed to a similar post in 2002.
Dillon competed in the 1952 Helsinki and 1956 Melbourne Olympics. He finished sixth on the “Stug” Perry-owned 5.5 metre yacht Unique in 1952 and four years later, in the same class, he won a silver medal on another of Perry’s 5.5 metre vessels, Vision. Dillon had crewed for Perry since 1948 and in 1951 they were joined by Neil Kennedy-Cochrane-Patrick, who was also a crew member in both Olympic boats. Dillon was appointed secretary of the Royal Yacht Squadron in 1966.