He was the working class boy from Manchester whose intensity and natural honesty made him British television's most bankable actor. He studied at the Royal Academy of Dramatic Art. His first starring role on TV was as Sgt John Mann in Redcap (1964). His first great success, though, was as Detective Inspector Regan in The Sweeney (1975). Violent and uncompromising, the series changed the portrayal of police work on British television and was one of the defining dramas of the 1970s.

For Inspector Morse (1987), Thaw was yet again cast as a policeman, but this time a more cultured character than Regan. The leisurely-paced series, set in beautiful Oxfordshire, was Thaw's most popular and long-running project. It established him as British television's most bankable actor, and during the 1990s he had many other starring vehicles. He was also a favourite of film director Richard Attenborough, who cast him in Özgürlük Çığlığı (1987) and Chaplin (1992).

John Thaw was a quiet, private man. His marriage to actress Sheila Hancock was generally regarded as one of the strongest in showbusiness. When he died at the age of 60, the BBC website was inundated with tributes from the viewing public. His "Inspector Morse" co-star Kevin Whately simply described him as the country's finest screen actor.