He appeared in the BBC sitcom Are You Being Served?, playing original character Mr (Cuthbert) Rumbold, the manager of the fictional Grace Brothers department store.

began with a pilot episode in 1972, with Smith playing Mr Cuthbert "Jug Ears" Rumbold, the manager of the menswear and ladieswear departments in a large fictional London store called Grace Brothers.

Following the death of Frank Thornton on 16 March 2013, Smith was the last surviving member of the original cast of Are You Being Served?

From September 1972, in contrast to his contemporaneous work in Are You Being Served?, he also had a semi-regular role as PC Jeff Yates in the series Z-Cars.

His film work included appearances in Salt and Pepper (1968), A Walk with Love and Death (1969), The Champions-Project Zero (1969), The Twelve Chairs (1970), dubbed in an Italian version of The Canterbury Tales (1972) directed by Pier Paolo Pasolini, and The Adventure of Sherlock Holmes' Smarter Brother (1975) as Hunkston, Sigerson Holmes' servant.

He played Mr. Simpkins (a miserable and desperately unattractive leisure centre manager who had rings run around him by two lazy, womanizing Australian criminals who had taken jobs in the leisure centre as a cover for their crimes) in The Sweeney, episode Golden Fleece in 1975.

He died on 6 December 2015 following seven weeks of hospitalization for a head injury from a fall at his home in Sutton, London.