He also appeared in the original West End and Broadway productions of Alan Bennett's The History Boys, as well as the 2006 film.
He has also appeared in Yes, Prime Minister, Kit Curran, The Labours of Erica, Bergerac, Mann's Best Friends, Double First, Drop the Dead Donkey, Time Riders, Pie in the Sky, The Tomorrow People, Mortimer's Law, The Bill, Believe Nothing, Midsomer Murders (twice), Foyle's War, Lewis and The Brief.
He played Bob Cratchit in a 1977 BBC adaptation of A Christmas Carol (opposite Michael Hordern as Ebenezer Scrooge), Mark Corrigan's father in the 2010 Peep Show Christmas special, and Clement Attlee in the 2012 TV movie Bert and Dickie.
He was the forger in the 1981 film Escape to Victory and also played Bartholomew Sholto in The Sign of Four (1983), Desmond Fairchild in An Awfully Big Adventure (1995) and the lawyer in Saving Grace (2000).
[3] Merrison has also appeared in other BBC radio series and plays, including Groosham Grange; Burn the Aeneid!