Dev Patel

Srinivasa Ramanujan

Jeremy Irons

G. H. Hardy

Toby Jones

Littlewood

Devika Bhise

Janaki

Stephen Fry

Sir Francis Spring

Kevin McNally

Major MacMahon

Jeremy Northam

Bertrand Russell

Anthony Calf

Howard

Pádraic Delaney

Beglan

Shazad Latif

Chandra Mahalanobis

Roger Narayan

Scribe

Arundathi Nag

Komalatammal

Dhritiman Chatterjee

Narayana Iyer

Richard Johnson

Vice Master Henry Jackson

Raghuvir Joshi

Narasimha

Malcolm Sinclair

Professor Cartwright

San Shella

Dr. Muthu

Richard Cunningham

Hobson

Thomas Bewley

Baker

Pip Barclay

Student

David Shaw-Parker

Porter

Dominic Cazenove

Waiter

Nicholas Agnew

Andrew Hartley

Alan Booty

Grocer

Shenagh Govan

Postal Worker

Alexander Forsyth

Cadet

Enzo Cilenti

Doctor

Elaine Caulfield

Hospital Nurse

Alex Bartram

Hospital Doctor

Christopher Ravenscroft

J. J. Thompson

Imogen Sage

Nursie (uncredited)