Thomasin McKenzie

Rose Davenport

Ben Radcliffe

Eric Noone

Emma Laird

Poppy Davenport

Damian Lewis

Lord Davenport

Katherine Waterston

Lady Davenport

Lizzie Hopley

Phyllis Davenport

Tom Felton

Archibald

Tom Goodman-Hill

Inspector Watt

Sue Johnston

Great Aunt Bonaparte

Lee Boardman

Karl

Anna Maxwell Martin

Mrs. McAllister

Jimmy Carr

Vicar

John Thomson

Bill

Tim McMullan

Cyril

Ramon Tikaram

Darvesh Khalid

Charlie Rawes

Big Alan

Hayley Mills

Older Rose Davenport (voice)

Adam Woodward

Bert Chester

Lily Knight

Fifi Valentine

Alex Butler

Lionel Gritt

Erin Austen

Mary Bechdel / Constance Bechdel

Jason Done

J.R.R. Tolkien

Laurie Ogden

Patricia

Paula Wharton

Mrs. Kitchen

Nathan McMullen

Alexander

Karen Henthorn

Sister Jude

Ian Bartholomew

Austin Blaine

Dean Fagan

Prison Guard

Gemma Wardle

Gladys

Brainard Oyani

Prospective Hall Boy

Magdalena Sverlander

Rose Seller

Nathan Hall

(uncredited)