His television work is extensive, including leading roles in many single dramas and TV plays, including the films Made in Britain, CH4, and Contact.
One of his earlier television appearances was as Coleman, part of a kidnapping gang in the hard-hitting police drama The Professionals; episode The Acorn Syndrome (1980).
He has also featured in various episodes of French & Saunders and in Absolutely Fabulous.
He appeared in the episode The Raven in the Foregate from the third series of Cadfael in 1997 as a medieval murder suspect and spy.
Chapman played Peter Tracey in the Doctor Who spin-off K-9 and Company in 1981 on BBC1.