The crooks in London know how it works. No one carries guns and no one resists the police. Then a new gang appears that go one better. They dress as police and steal from the crooks. This upsets the natural order of the police/criminal relationship and the police and the crooks join forces to catch the IPOs (Impersonating Police Officers), including an armoured car robbery in which the police must help the gangs to set a trap.
Peter Sellers
Pearly Gates
Lionel Jeffries
Inspector Fred 'Nosey' Parker
Bernard Cribbins
Nervous O'Toole
Nanette Newman
Valerie
Davy Kaye
Trainer King
Bill Kerr
Jack Coombes
Ed Devereaux
Bluey May
Reg Lye
Reg Denton
