When Newman decides she doesn't want to be burdened with children, she decides to take the pill--which, as we all know from those ubiquitous posters of the 1960s, was a "No No" so far as the Pope was concerned.

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 upset's 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 armored car robbery in which the police must help the gangs to set a trap.