[4] Beginning as an actor, Garnett appeared in An Age of Kings (1960), the BBC's mounting of Shakespeare's eight contiguous history plays, the courtroom film The Boys (1962), Edgar Wallace Mysteries episode Incident At Midnight (1962), several television plays by David Mercer, and an episode Catherine (1964) in the Teletale series, significant for his career because it led to his first meeting with its director, Ken Loach.
[8] Together with dramatist David Mercer, fellow producers Kenith Trodd and James MacTaggart, and literary agent Clive Goodwin, Garnett founded Kestrel Productions, which was conceived as an autonomous unit connected with London Weekend Television.
LWT required Garnett and his colleagues to mainly use their television studio and record on video tape, only allowing them to shoot on film and on location occasionally.
[12] A two-part Play for Today, The Price of Coal (1977), reunited Garnett and Loach with Barry Hines, and was their response to the silver jubilee of the Queen, mixing that celebration with a fatal accident involving two miners, similar to the events of the Cadeby Main pit disaster.
The Spongers (1978), written by Allen and directed by Roland Joffé, also used the background of the silver jubilee, this time in the context of government spending cuts in the welfare state, in particular the closure of facilities used by a child with learning difficulties.
[13] Garnett produced G. F. Newman's Law and Order (1978), a quartet of dramas looking at the failings of the British criminal justice system.
After relocating to the United States, Garnett lived by the principle "a movie should never be about what it's about" meaning that, although Earth Girls is disguised as a space comedy about aliens and Follow That Bird (1985) is a Sesame Street style children's film, the real theme of these motion pictures is racial prejudice.
[17][18] In 2009, an email by Garnett was circulated within the television industry, and published online, in which he argued that the BBC's management techniques "stifle the creativity which the organisation is supposed to be encouraging".