Mickey Rooney
— Timothy Dennis
Edmund Gwenn
— Headmaster Justin
Ian Hunter
— Roger Carlton
Freddie Bartholomew
— Peter Carlton
Marta Linden
— Winifred Dennis Carlton
Juanita Quigley
— Jane 'The Runt' Dennis
Alan Mowbray
— Mr. Duncan
Peter Lawford
— Ronnie Kenvil
Raymond Severn
— 'Inky' Weeld
Harry Duff
— Eton Student (uncredited)
Robert Lynn
— Eton Student (uncredited)
Tina Thayer
— Flossie Sampson (uncredited)
Alan Napier
— Willow Club Restauranteur (uncredited)
Bess Flowers
— Party Guest (uncredited)