As Dave Rolinson's book (see 'Further reading', below) on Clarke details, between 1962 and 1966 Clarke directed several plays at The Questors Theatre in Ealing, London. Between 1967 and 1969 he directed various ITV productions including plays by Alun Owen (Shelter, George's Room, Stella, Thief, Gareth), Edna O'Brien (Which of These Two Ladies Is He Married To? and Nothing's Ever Over) and Roy Minton (The Gentleman Caller, Goodnight Albert, Stand By Your Screen). He also worked on the series The Informer, The Gold Robbers and A Man of Our Times (but not, as Sight and Sound once claimed, Big Breadwinner Hog). Clarke continued to work for ITV through the 1970s but now made much of his work for the BBC. This included pieces for The Wednesday Play (Sovereign's Company 1970), Play for Today and Play of the Month (The Love-Girl and the Innocent, 1973 and Danton's Death, 1978). Distinctive work for these strands included further plays by Minton including Funny Farm (1975) and Scum (further details below), but also Sovereign's Company (1970) by Don Shaw, The Hallelujah Handshake (1970) by Colin Welland and Penda's Fen (1974) by David Rudkin. He also made To Encourage the Others (1972), a powerful drama documentary about the Derek Bentley case, the case which was later dramatised in the 1991 film Let Him Have It by Peter Medak, and several documentaries, including Vodka Cola (1981) on multinational corporations.