Courtney’s first Doctor Who appearance was in 1965’s ‘The Daleks’ Master Plan’, playing Space Security Agent Bret Vyon opposite William Hartnell as the First Doctor.
Pleased with his performance, several years later director Douglas Camfield cast Courtney in 1968’s ‘The Web Of Fear’ as Colonel Lethbridge-Stewart, after the original actor gave up the role. The character returned later that year as a Brigadier in ‘The Invasion’ and was a semi-regular cast member between 1970 and 1975, returning in 1983 and 1989.
Courtney was reunited with Elisabeth Sladen as Sarah Jane Smith in a two-part story of The Sarah Jane Adventures in December 2008, ‘Enemy Of The Bane’.
In addition to his Doctor Who work, Courtney also made guest appearances in cult series The Avengers, The Champions and Randall & Hopkirk (Deceased) in the 1960s.