James Corden

Paul Potts

Alexandra Roach

Julz

Julie Walters

Yvonne

Colm Meaney

Roland Potts

Jemima Rooper

Hydrangea

Mackenzie Crook

Braddon

Trystan Gravelle

Matthew

Sion Tudor Owen

Choirmaster

Alex Macqueen

Dr. Thorpe

Miriam Lucia

Signora Fiorentino

Stanley Townsend

Luciano Pavarotti

Di Botcher

Nurse

Jon Wennington

Talent Show Punter (uncredited)

Owen Hunte

Friend in Bar (uncredited)