He used the surname Cato in his early stage career, but after writing Sparrows Can't Sing he was urged by his agent to use his real name.

In addition, Lewis played a coach driver with very similar characteristics to Blakey in a 2000 edition of ITV's 1970s-set sitcom The Grimleys.

The films in which Lewis acted included A Prize of Arms (1962), Sparrows Can't Sing (1963) (which he also wrote), Negatives (1968), Staircase (1969, with Richard Burton and Rex Harrison), Some Will, Some Won't (1969), The Magnificent Seven Deadly Sins (1971), The Last Remake of Beau Geste (1977), Personal Services, Out of Order (both 1987), and The Krays (1990).

The character appeared in many episodes for 17 years, until ill health forced Lewis to leave the series and retire in 2007.

In 1996, Lewis played Harry Lambert, the signalman, in the BBC pilot of sitcom Oh, Doctor Beeching!, which ran to two further series.