Domhnall Gleeson as Tim Lake

Rachel McAdams as Mary

Bill Nighy as Dad

Tom Hollander as Harry

Margot Robbie as Charlotte

Lydia Wilson as Kit Kat

Lindsay Duncan as Mum

Richard Cordery as Uncle D

Joshua McGuire as Rory

Will Merrick as Jay

Vanessa Kirby as Joanna

Tom Hughes as Jimmy Kincade

Clemmie Dugdale as Ginger Jenny

Harry Hadden-Paton as Rupert

Mitchell Mullen as Mary's Father, Fitz

Lisa Eichhorn as Mary's Mother, Jean

Jenny Rainsford as Polly

Natasha Powell as Aunty May

Mark Healy as Dans le Noir Maître D'

Ben Benson as Theatre Deserter

Philip Voss as Theatre Judge

Tom Godwin as Prompter

Pal Aron as Bhattie QC

Catherine Steadman as Tina

Andrew Martin Yates as Wedding Priest

Charlie Barnes as Posy (Newborn)

Verity Fullerton as Posy (6 Months)

Veronica Owings as Posy (1 Year)

Olivia Konten as Posy (2 1 / 2 - 3 Years)

Sarah Heller as Posy (5 Years)

Jaiden Dervish as Boy Posy

Jacob Francis as Jeff (Newborn)

Jago Freud as Jeff (5 Months)

Ollie Phillips as Jeff (2 Years)

Sophie Pond as Jo (6 Months)

Sophie Brown as Jo - 1 Year

Molly Seymour as Trudy (Party Guest)

Matilda Sturridge as Flirty Girl

Tom Stourton as John

Rebecca Chew as Pret a Manger Server

Jon West as Court Clerk

Graham Richard Howgego as Judge

Kerrie Liane Studholme as Jury Foreman

Kenneth Hazeldine as Defendant

Barbar Gough as Jazz Singer

Jon Boden as Busker

Charlie Curtis as Young Tim

Richard Griffiths as Lawyer in Play (uncredited)

Richard E. Grant as Lawyer in Play (uncredited)

Haruka Abe as Japanese Girl (uncredited)

Lee Nicholas Harris as Police Officer (uncredited)

Matthew C. Martino as Commuter (uncredited)

Tom Coulston as Theatre Attendee (uncredited)

Jon Wennington as Paralegal (uncredited)