Patrick Holt
Inspector Gregory
Emrys Jones
Howard Rogers
Honor Blackman
Ann Rogers
Bruce Beeby
Det. Sgt Conway
John Horsley
Mr. Fisher
Robert Perceval
Bank Manager
Wally Patch
Barman
Frank Pettitt
Fred (as Frank Pettit)
Benedicta Leigh
Policewoman Scott
Peter Glaze
Station Booking Clerk
Vi Stevens
Landlady
Howard Greene
River Police Sergeant
Raymond Smith
River Police Constable
Lawrence James
Uniformed Constable
Reginald Hearne
Doctor (as Reggie Hearne)
Barry Linehan
Forensic Chemist
Gerry Duggan
Norman Cole
Colin Rix
Plain Clothes Detective
Bill Mills
Photographer
Pat Shaw
Uniformed Policewoman
John Tatham
PC Barrow (uncredited)