Dev Patel

Character: Srinivasa Ramanujan

Jeremy Irons

Character: G. H. Hardy

Toby Jones

Character: Littlewood

Devika Bhise

Character: Janaki

Stephen Fry

Character: Sir Francis Spring

Kevin McNally

Character: Major MacMahon

Jeremy Northam

Character: Bertrand Russell

Anthony Calf

Character: Howard

Pádraic Delaney

Character: Beglan

Shazad Latif

Character: Chandra Mahalanobis

Roger Narayan

Character: Scribe

Arundathi Nag

Character: Komalatammal

Dhritiman Chatterjee

Character: Narayana Iyer

Richard Johnson

Character: Vice Master Henry Jackson

Raghuvir Joshi

Character: Narasimha

Malcolm Sinclair

Character: Professor Cartwright

San Shella

Character: Dr. Muthu

Richard Cunningham

Character: Hobson

Thomas Bewley

Character: Baker

Pip Barclay

Character: Student

David Shaw-Parker

Character: Porter

Dominic Cazenove

Character: Waiter

Nicholas Agnew

Character: Andrew Hartley

Alan Booty

Character: Grocer

Shenagh Govan

Character: Postal Worker

Alexander Forsyth

Character: Cadet

Enzo Cilenti

Character: Doctor

Elaine Caulfield

Character: Hospital Nurse

Alex Bartram

Character: Hospital Doctor

Christopher Ravenscroft

Character: J. J. Thompson

Imogen Sage

Character: Nursie (uncredited)