Talulah Riley as Annabelle Fritton

Rupert Everett as Camilla Fritton / Carnaby Fritton

Gemma Arterton as Kelly Jones

Colin Firth as Geoffrey Thwaites

Lena Headey as Miss Dickinson

Jodie Whittaker as Beverly

Russell Brand as Flash Harry

Anna Chancellor as Miss Bagstock

Juno Temple as Celia

Tamsin Egerton as Chelsea Parker

Antonia Bernath as Chloe

Amara Karan as Peaches

Paloma Faith as Andrea

Kathryn Drysdale as Taylor

Lily Cole as Polly

Holly Mackie as Tara

Cloe Mackie as Tania

Lucy Punch as Verity Thwaites

Fenella Woolgar as Miss Cleaver

Celia Imrie as Hausmutter

Toby Jones as Schatzmeister

Caterina Murino as Miss Maupassant

Stephen Fry as Stephen Fry

Mischa Barton as JJ French

Tereza Srbova as Anoushka

Millie Foster as Saffron

Nathaniel Parker as Chairman of the National Gallery

Cheryl as School Band Member

Nadine Coyle as School Band Member

Sarah Harding as School Band Member

Nicola Roberts as School Band Member

Kimberley Walsh as School Band Member

Esme Thompson as 1st Year Bookie

Bel Parker as Aerial Girl

Theo Cross as Art Teacher

James Rawlings as Press Secretary

Ben Willbond as Damaged Inspector

Emily Bevan as Female Inspector

John Thompson as Male Inspector

Steve Furst as Bank Manager

Preston Thompson as Boy at the Party

Cato Sandford as Bedales Pupil 1

Jonathan Bailey as Bedales Pupil 2

Denise Stephenson as Denise

Andrew Buckley as Guard

Jody Halse as Guard

Richard Glover as Floor Runner

Jeremy Thompson as Sky Newscaster

Cloi Mckee as Tania

Rene Costa as Paramedic (uncredited)