Blair made her first stage appearance at the Strand Theatre on 3 October 1963 playing the part of Philia in the London debut of A Funny Thing Happened on the Way to the Forum.

She joined the Royal Shakespeare Company for their 1971 season, during which she portrayed Emilia in The Man of Mode and Aglaya in Subject to Fits.

Her other film appearances include A Flea in Her Ear (1968), Battle of Britain (1969), Taste the Blood of Dracula (1970), Indiana Jones and the Last Crusade (1989, as the wife of her real-life husband Julian Glover, and credited as Mrs. Glover), Valmont (1989), The Monk (1990), The House of Angelo (1997), The Match (1999), Mrs Caldicot's Cabbage War (2002), AfterLife (2003) and Johnny English Reborn (2011).

[4] Blair guest starred in two episodes of Space: 1999; appearing in 1975, along with Anthony Valentine, in War Games and in 1976, along with Freddie Jones, in Journey to Where.

She played a principal role (Sally) in the BBC's alternative history TV serial An Englishman's Castle, first broadcast in 1978.

She played the part of a foreign agent, disguised as a bride, in The Avengers episode "A Funny Thing Happened On The Way To The Station".