BBC Wimbledon commentator Mark's finest hour as a player was as a member of the Great Britain team which reached the final of the 1978 Davis Cup against the USA. In the semi-final against Australia, he partnered David Lloyd to victory in the deciding doubles rubber. Mark won 10 singles tournaments between 1970 and 1977, was twice a quarter-finalist in the Australian Open, reached the quarter-finals of the US Open in 1966, and was runner-up at Queen's in 1977.