Early in her career she appeared in 22 episodes of Strangers as WDC Vanessa Bennett.
In the 1987 television mini-series A Perfect Spy, based upon the novel by John Le Carré, Mollison portrayed the incisive wife of a recruitment officer within British intelligence.
Mollison appeared in the role of "Annie" in the 1992 BBC adaptation of Joseph Conrad's novel, The Secret Agent (with David Suchet, Cheryl Campbell and Janet Suzman).
Mollison is married to the director David Gilmore.[3] She met Gilmore when she got a part in a play he was directing, Move Over Mrs Markham, where she played the au-pair.[2] They have three sons, Charles, George and Edward, and live in Wimbledon, London, England. They also have a house in France, and she enjoys yoga and interior design in her spare time.[2]