He was best known for playing Chief Guard Barnes who processes Alex in A Clockwork Orange, Cyril Blamire in Last of the Summer Wine (1973–1975), and Rangi Ram in It Ain't Half Hot Mum (1974–1977).

On radio, he played a variety of characters in the BBC's long-running comedy series The Navy Lark, including Able Seaman Ginger, Lieutenant Bates, Rear Admiral Ironbridge, the Padre, and Captain Ignatius Aloysius Atchison.

Bates appeared in many British television series, including Last of the Summer Wine from 1973 to 1975 (as Cyril Blamire) and It Ain't Half Hot Mum from 1974 to 1977 (as Rangi Ram).

[13][15] The series has been repeatedly shown on the "That's TV (UK)" channel since the summer of 2023, with an on-screen 'disclaimer' at the beginning of each episode reminding viewers that it contains language and attitudes reflecting the era in which it was made.

Bates's film roles include Bedazzled (1967) as the flirtatious police inspector, Here We Go Round the Mulberry Bush (1967) as Mr. McGregor, Battle of Britain (1969) as Warrant Officer Warwick, Oh!

On stage, he played Shakespearean roles at Stratford and at the Old Vic and made a big impression as Inspector Truscott in the West End production of Loot by Joe Orton in 1966.