In 2000 Thea won the James Menzies-Kitchin young director of the year award, making her directorial debut with a production of Caryl Churchill's Top Girls, which transferred to the west end and toured the UK twice.

Thea was then made Britain's youngest artistic director when she took over the Southwark Playhouse for three years, before then going on to be the artistic director of the Gate Theatre in Notting Hill. Since then as a freelance director, her credits include productions for the Almeida and the Donmar, the National Theatre and many in the west end including Equus with Daniel Radcliffe and Richard Griffiths (also Broadway), The Misanthrope with Keira Knightly, Heroes with John Hurt, Cause Célèbre with Anne-Marie Duff at the Old Vic. Her production of After The Dance for the National Theatre won 8 major awards.

She has also directed Henry V starring Tom Hiddleston for Sam Mendes/Neal Street and the BBC, as well as the 2013 Christmas Special of Call The Midwife also for Neal Street and the BBC. She directed Richard Griffiths in his last stage performance, in The Sunshine Boys with Danny DeVito at the Savoy Theatre before directing her first musical, The Bodyguard at the Adelphi. The Bodyguard has gone onto play all over the world including, America, Australia, South Korea, Germany and China.  She directed Miranda Hart in her arena tour for 2014, as well as Kevin Spacey in his first one-man show, Darrow for the Old Vic.

Thea’s debut feature film, Me Before You, an adaptation of Jojo Moyes’ novel for MGM starring Emilia Clarke and Sam Claflin, broke $200 million at the box ofiice.

She is currently developing a musical with Working Title Films, as well as a new play produced by Sam Mendes’ Neal Street, while in Pre-Production for Disney’s live action film The One And Only Ivan, due for release in 2019.