television roles include Myra Booth in Coronation Street, Kate in Take Three Girls and Jessie Seaton in When the Boat Comes In. She played Emma Lambe in the third series of All in Good Faith, and John Duttine's second wife in the BBC drama To Serve Them All My Days. She also starred in a children's comedy series, Bad Boyes, in which she played the eponymous lead character's mother (two series, 1987–88).
She has featured with her husband, Bolam, in several series including an early episode of The Likely Lads, New Tricks, Grandpa In My Pocket and an ITV legal drama entitled Close and True (screened in 2000), which also starred Robson Green.
Her guest appearances include UFO, Space: 1999, Z Cars, Special Branch, Dalziel and Pascoe, Hi-de-Hi! and Holby City.
In 2009, she was one of five actresses (alongside Emilia Fox, Barbara Flynn, Samantha Bond and Diana Quick) to portray Queen Elizabeth II in Channel 4's series The Queen.
She is also a regular in BBC produced Doctor Who audios, playing Mrs Wibbsey, the Doctor's housekeeper, in three series with Tom Baker, Hornets' Nest (2009), Demon Quest (2010) & Serpent Crest (2011). This was not her first foray in to the world of Doctor Who having played Mrs Moynihan in an early Big Finish Productions Doctor Who audio play, The Spectre of Lanyon Moor opposite Colin Baker and Nicholas Courtney. Jameson is also known as an audio book narrator, especially of Catherine Cookson novels.
He enjoyed success as a classical stage actor, then played roles on British television. Shakespearean roles on TV include Demetrius in A Midsummer Night's Dream (1968), Gratiano in The Merchant of Venice (1973) and Edmund in King Lear (1975). An early recurring television role was as civil servant Dowling in the final series of boardroom drama The Power Game in 1969.
In 1970 he played Henry Ireton in Cromwell. In 1971, he starred as Tsar Nicholas II of Russia in the film Nicholas and Alexandra, then in 1973 took the lead role of Mr Rochester in a BBC adaptation of Jane Eyre opposite Sorcha Cusack. He appeared as Gratiano opposite Laurence Olivier as Shylock in the National Theatre's film The Merchant of Venice (1974). He made two appearances in the anthology series Thriller in 1974 and in 1975 played Quiller, a spy who never used a gun, in the British TV series of the same name. He appeared as Dornford Yates' gentleman hero Jonathan Mansel in the 1977 BBC adaptation of She Fell Among Thieves. In 1979 he played Peter Guillam opposite Alec Guinness in the serial Tinker, Tailor, Soldier, Spy. He also played Mr Spooner in series Tracy Beaker Returns in 2010.
In 1986 Jayston played the role of the Valeyard in the long-running British science fiction television series Doctor Who. In the serial The Ultimate Foe, the Valeyard is revealed to be an evil version of the Doctor himself. He later reprised the part of the Valeyard in He Jests at Scars..., an audio play in the Big Finish Productions' Doctor Who Unbound series.
Jayston played Neville Badger in the 1989 television adaptation of David Nobbs's comedy of manners A Bit of a Do. He portrayed James Bond in a radio adaptation of You Only Live Twice in 1990. In 1991 he appeared as Colonel Mustard in the television series Cluedo and a year later made a guest appearance in the Press Gang episode "UnXpected". Other TV appearances include in EastEnders, Coronation Street, Only Fools and Horses, The Darling Buds of May, Tales of the Unexpected, The Bill and the character of Donald De Souza in Emmerdale. He also was on Holby City and Tracy Beaker Returns