The daughter of a baronet of Langrishe, born in London, her parents moved to Kent when she was aged six, where she and her sister were brought up. She trained at the Elmhurst Ballet School, but after deciding that she couldn't become a soloist for the Royal Ballet, decided to move into acting.
In 1976, Langrishe appeared in the BBC production of The Glittering Prizes. The next year, aged 18, she played the role of Kitty in the BBC1 adaptation of Anna Karenina, before working in the theatre with Peter Gill.
Her first big part was in the 1978 British adaptation of Les Misérables. She also starred as Jane Winters in the futuristic BBC Play for Today episode The Flipside of Dominick Hide (1980) and its follow up, Another Flip for Dominick (1982) both by Jeremy Paul and Alan Gibson. She played Janet Hollywell, wife of Fred Hollywell, in the 1984 film adaptation of Charles Dickens' A Christmas Carol, starring George C. Scott.She also appeared in one episode of Minder in 1984, as Julie, a journalist.
On stage she played in Kenneth Branagh's production of Twelfth Night. She became a leading actress, taking the female lead in the BBC detective series Pulaski in 1987 and appearing in several episodes of Chancer in 1990.
Langrishe is perhaps best known for her role as Charlotte Cavendish in the BBC series Lovejoy in which she starred for two series in 1993-94. After appearing in a series of episodes of The Good Sex Guide in the mid-1990s, she appeared in Sharpe's Regiment (1996) and Sharpe's Justice (1997) as the Dowager Countess Anne Camoynes. She played the unhappy landlady to Hywel Bennett's professional scrounger James Shelley in the 5th series of Shelley on ITV. She has also starred in Heartbeat, in the episode Echoes of the Past in December 1998.
From 2001 to 2007, she appeared as regular character Georgina Channing, Donald Sinden's daughter, alongside Martin Shaw in the BBC TV drama Judge John Deed, playing his ex-wife and then joined the BBC medical dramaCasualty, playing executive director Marilyn Fox. In 2010 she played Ros, an 'older woman' in an open marriage in Pete Versus Life on Channel 4.
In September 2010 she played the character of Susan Fincher in an episode of Midsomer Murders entitled Blood on the Saddle
Langrishe married the actor Patrick Drury in London on 15 November 1984, but the couple divorced in 1995 after having two daughters, Rosalind and Leonie. She presently lives in Putney, and her hobbies include rowing, running, swimming and tennis.