In stage productions of Shakespeare, she's starred in A Midsummer Night's Dream and Twelfth Night.
She is a good tennis player and represented Sussex before she became an actress. She now plays in pro-celebrity tournaments.
Haydn was nominated for a 2006 Laurence Olivier Award (Best Actress in a Musical) for her performance as the dance mistress in Billy Elliot: the Musical at the Victoria Palace Theatre, London.
Apart from English, she speaks French and Italian fluently.
During the 1980s, she spent five years in Rome as a teacher of English.
For the role of the dance mistress in Elton John's adaptation of the movie Billy Elliot as a stage musical, Haydn had to sing. One of her songs was called Born to Boogie, and she usually turned a cart-wheel while performing it.
Haydn regularly does voice-work in BBC Radio 4 drama productions.
She now records audio books, showing a great talent for accents from around the world. For the audio book of Peter Carey's prize-winning novel My Life as a Fake, the accents Haydn provided included South African, Australian, and Tamil.
Haydn's father, Guy Thomas Gwynne, was a printer at Haywards Heath in West Sussex, England. He died in 1994, when Haydn was in her early thirties.
Haydn appears in Julia Taylor-Stanley's new movie, These Foolish Things (2006).
Haydn lives in London with her partner, Jason Phipps, a psychotherapist.
Haydn now has two sons, Orlando (born in 1997) and Harry (born 2000).
Haydn Gwynne: You have to enjoy the time the kids want to spend with you while you can. All too horribly soon you're going to be the most boring person they know. (interview in 'Woman' magazine, May 2003)
Haydn Gwynne: When I lived in Italy, I fell in love totally with skiing. I even fantasized about giving it all up to become a ski instructor. (interview in 'Candis', July 2002)
Haydn Gwynne: It was the musical nightmare to end them all. My biggest regret is that I didn't keep a daily diary. The most extraordinary things happened. The star and the director were fired after press night; it was rewritten. It did have its moments - my costume was worth £10,000 - but mainly it was agony. I cried myself to sleep most nights. (on Harold Fielding's musical 'Ziegfeld', 1988)
Haydn Gwynne: No musical is easy. It's a whole different beast from a play. There are just so many elements to fit together - the choreography, the music, the direction - and you're constantly reminded of how much it's all cost. That financial pressure is in the air. (interview in 'Daily Telegraph', 23 April 2005)
Haydn Gwynne: Having children changes your choices. (interview in 'TV Mag', July 2001)
Haydn Gwynne: I am one of life's guests rather than one of life's hosts, I am afraid. (interview in 'The Lady', May 2005)
Haydn Gwynne (in 'Drop the Dead Donkey'): Dave, I'm afraid I'm going to have to stab you.