Dr. Jankers
Cardew Robinson (as Cardew 'The Cad' Robinson)
'The Private Eye'
Matron
Maisie
Mlle. Praline
Mr. Winkle
Harry The Scar
Ferdy
Fanshaw
Chumleigh (as Ronald Corbett)
Horsetrough
Fudge-The Porter
Mc. Tavish
Fatty Gilbert
Prof. Stromboli
The Potter
Station Sergeant
Constable
The Guide
Themselves
Heckling Boy at Concert (uncredited)
Museum Attendant (uncredited)
(uncredited)
Schoolboy in audience (uncredited)
Second Museum Attendant (uncredited)