Tamsin Olivia Egerton commonly known as Tamsin Egerton (born 26 November 1988) is an English actress and model best known for her roles of Chelsea Parker in the 2007 film St Trinian's, and Holly Goodfellow in Keeping Mum. Egerton started her acting career age six, following her older sister, Sophia to a local youth theatre, saying; ""The whole reason I'm acting now is because I wanted to be doing what my big sister was doing". A year later, she appeared in a Royal Shakespeare Company musical production of The Secret Garden, playing Mary. Egerton's other film credits include Sarah in Driving Lessons (2006) alongside Rupert Grint, and Flora in Knife Edge (2008). Her role as Holly Goodfellow in the 2005 film Keeping Mum sparked controversy as she appeared topless at the age of 16. She was to appear as Katrina in Eragon, but the scenes which she featured in were removed from the final cut. Egerton starred as Princess Elenora in the TV children's series Sir Gadabout: The Worst Knight in the Land. In 2001, she starred as the "young" Morgaine in the TV mini series The Mists of Avalon. She has also appeared on stage - in the RSC's musical version of The Secret Garden. In 2009 Egerton appears in the St Trinian's sequel, St. Trinian's II: The Legend of Fritton's Gold. In 2010 it was confirmed that Egerton will play Guinevere in the new US Starz adaptation of Camelot. Also starring Joseph Fiennes, Eva Green and Jamie Campbell Bower.
She has a sister named Sophia. She attended Ditcham Park School near Petersfield in Hampshire, where she says she was bullied. She also states she truanted, preferring to go to modelling shoots; "I played truant all the time. I was modelling so I'd go to shoots and call in sick." After finishing school at 16 with nine A-grade GCSE's, Egerton decided to pursue acting rather than going to university or drama school, saying; "At drama school, they like to take you apart and rebuild you but I don't want to change now". She had a brief job as a babysitter for three children. She previously shared a flat in Marylebone, London, with her St Trinians castmate Talulah Riley, whom she described as her "soulmate". She now lives in Hampstead with theatre producer Jamie Hendry. She has cited Takeshi Kitano as her favourite film director, and said; "I’d love Takeshi Kitano to put me in a martial arts film so I’d have an excuse to practice all the time". Egerton has previously dated semi-professional footballer and former Hollyoaks cast-member, Andy Jones.