[1][2] He is possibly best known for his role as Oliver Lacon in the BBC television adaptations of the John le Carré novels Tinker Tailor Soldier Spy and Smiley's People and his role as Bret Renssalaer in Len Deighton's trilogy Game, Set and Match.

Bate's other credits include: Dixon of Dock Green, The Saint, The Avengers, Prime Suspect, Inspector Morse, A Touch of Frost and Midsomer Murders.

Bate's first television appearance was in 1955 and from then on he appeared as: James in Pinter's The Collection, Rogojin in The Idiot, MacDuff in Macbeth, Javert in Les Misérables, the title role in Grady (a trilogy), T H Huxley in Darwin’s Bulldog, Nikolai in Fathers and Sons, Creon in King Oedipus, Victor Hugo in Ego Hugo, Harry Paynter in Intimate Strangers, The Dutch Train Hijack 1976, Dr Dorn in The Seagull 1977, Kim Philby in Philby, Burgess and Maclean 1977 (nominated Best Actor Monte Carlo Festival 1978), An Englishman's Castle (1978), the title role in The Trial of Uri Urlov 1978, Tinker Tailor Soldier Spy 1978, Crime and Punishment 1979, Tis Pity She's A Whore 1980, The Human Crocodile 1980, “Fanny by Gaslight” 1981, Smiley's People 1982, A Woman Called Golda (with Ingrid Bergman) 1982, J A D Ingres in Artists and Models 1983, Shackleton, Game, Set and Match (TV mini series 1988), War and Remembrance 1988, Inspector Morse (Dr Crowther in Last Bus to Woodstock) 1988, Countdown to War 1989, Agatha Christie's Poirot 1990, Medics 1991 and 1992, Prime Suspect 1994, Rebecca 1996, A Touch of Frost 1996, Bodyguards 1996, Silent Witness 1997, Midsomer Murders 2000.

Bate's film credits include Dentist in the Chair (1960), Dentist on the Job (1961), Payroll (1961), A Prize of Arms (1962), Act of Murder (1964), Ghost Story (1974), Give My Regards to Broad Street (1984), Eminent Domain (1990) and Nowhere in Africa (2001) (winner Oscar for Best Film in a Foreign Language).

On 22 May 1954, he married Diana Fay, the daughter of Kenneth Alfred Charles Caws Watson (d. 29 October 1940), of Seaview, Isle of Wight.