Something unusual is happening in London's criminal underworld. A new gang of crooks from Australia is going around dressed as police officers and lifting the ill-gotten gains of the local crooks. Things soon escalate, and it gets to the point where the robbers start ambushing the actual cops, assuming they're beating up the Aussies.
Soon, the local rival gangs — including those led by "Pearly" Gates (Sellers), who daylights as a legitimate fashion designer, and "Nervous" O'Toole (Cribbins) — gather for an emergency meeting and vote to propose an alliance with the police to get the IPO gang out of the way, with Pearly as their representative. Hilarity Ensues as the two parties of strange bedfellows prepare for war on the IPO gang.
A young, uncredited Michael Caine appears briefly as a constable.
This film contains examples of:
- Anti-Hero: Pearly is a rather charismatic crook who runs a legitimate fashion shop and is the main protagonist and a driving force in the war against the IPO mob.
- Batman Gambit: Planned by heroes, anti-heroes, and villains alike.
- The Chessmaster: Pearly Gates develops into this over the course of the war against the IPO mob. This was played up in advertising.
- Crime-Concealing Hobby: Played with. While Nosy Parker immediately suspects that Pearly Gates is still using his fashion boutique as a front for his gang's activities, Pearly insists that the fashion boutique is now a legitimate business which he runs on the side.
- Deuteragonist: Nosy Parker.
- Enemy Mine: The local crooks and the police join forces against the IPO mob. The IPO mob also makes strange bedfellows of Pearly and Nervous.
- Even Evil Has Standards: The local crooks note that they wouldn't assault a police officer and apologise to Nosy Parker when they end up sloshing him instead of the IPO gang they'd been pursuing. Parker even makes note of how out of character that was of the two that hit him.
- Femme Fatale: Valerie.
- Funny Foreigner: German crook Siggy Schmoltz.
- Impersonating an Officer: The Australian gang uses this as their tactic.
- Ironic Echo: Parker and then Pearly mentioning their first meeting years before, which ended in Pearly's capture and each other's names stuck in their respective memories forever.
- Karma Houdini:
- Pearly escapes with the now-secured briefcase of money, Nosy Parker, and his two-timing girlfriend Valerie in tow and starts up a Hawaiian fashion shop, with Parker and Valerie (the latter as a model) in his employ.
- Also Valerie herself, who despite grassing on her boyfriend's gang's jobs to the IPO mob ends up escaping with him and being employed as a model for his Hawaiian fashion shop.
- Lovable Rogue: Pearly Gates.
- Malicious Misnaming: Pearly does this to Parker, calling him "Nosy". When Parker protests, Pearly counters with an Ironic Echo (see above).
- Noodle Incident: That one time years before when Parker brought Pearly in. They were Nosy Parker and Pearly Gates then, and Nosy Parker and Pearly Gates they'll always be!
- Out-of-Character Moment: Lampshaded by Nosy Parker when a couple of local crooks jump him.
- Pun-Based Title: An obvious play on "the long arm of the law".
- Running Gag: Parker accusing Pearly of trying to bribe him.
- Villain with Good Publicity: An anti-heroic example in Pearly Gates.
- Vitriolic Best Buds: Pearly and Parker develop into this by the end.
- What the Hell, Hero?: Parker chews out the paranoid crooks that assaulted him.Nosy Parker: A quite bit of breaking and entering is one thing, but sloshing a bogey in the execution of his dutyoh, dear, dear, dear!they'll really lay on for that!