A manhole opens at night in an empty street and out climbs Lieutenant-Colonel Norman Hyde (Jack Hawkins) in a dinner suit. He gets into a Rolls-Royce and drives home. There, he prepares seven envelopes, each containing an American crime paperback called The Golden Fleece, half of a £5-note and an unsigned invitation from “Co-operative Removals Limited” to lunch at the Cafe Royal.
The envelopes are sent to former army officers, each in desperate or humiliating circumstances. When they all turn up looking for the other half of the £5 notes which are handed out, Hyde asks their opinion of the novel which is about a robbery. They show little enthusiasm but Hyde then reveals each person's misdemeanors.
Hyde has no criminal record but holds a grudge for being made redundant by the army after a long career. He intends to rob a bank using the team's skills, with equal shares of £100,000 or more for each man.
The gang meet under the guise of an amateur dramatic society rehearsing Journey’s End to discuss the plan before moving into Hyde’s house and living a military regimen of duties and fines for being out of line. Hyde knows that a million pounds in used notes is regularly delivered to a City of London bank and has details of the delivery.
They raid an army training camp in Dorset for arms and supplies. Hyde, Mycroft, Porthill and Race distract soldiers by posing as senior officers on an unscheduled food inspection. The others steal weapons while posing as telephone repairmen, speaking in Irish accents to divert suspicion to the IRA.
The gang rent a warehouse to prepare. Race steals vehicles including cars and a truck which are fitted with false number plates. They are disturbed by a passing policeman who ironically offers to keep an eye on their premises as he patrols. In Hyde’s basement, the gang train with maps and models. On the eve of the operation, Hyde destroys the plans and recalls his former military glory.
The robbery is bloodless and precise. Using smoke bombs, sub-machine guns, and radio jamming equipment, the gang raids the bank, near St Paul’s. The money is seized without serious injury and the robbers escape. At Hyde’s house, celebrations are interrupted by the unexpected arrival of Hyde’s old friend, Brigadier “Bunny” Warren (Robert Coote), who drunkenly recalls the old days. One by one the members leave carrying suitcases filled with notes. Then the telephone rings; Hyde is told that police and soldiers surround the house.
Leading the police is Superintendent Wheatlock (Ronald Leigh-Hunt) from whom Hyde learns the flaw in his plan. A small boy outside the bank had been collecting car registration (licence plate) numbers, a common hobby at the time. The police, discovering the number, found it had been noted by the policeman who visited the warehouse. The policeman had also noted the number of Hyde's own car. Thus a link was established between the robbery and Hyde.
Hyde is escorted to a police van in which the rest are "all present and correct", each having been captured as he left the house.
Allied Film Makers was a short-lived production company founded by Dearden, actors Hawkins, Forbes and Attenborough, and producer Michael Relph. Forbes contributed many of the company's scripts. Dearden had previously directed The Blue Lamp.
The portrait of Hyde's wife (he comments "I regret to say the bitch is still going strong") is a close copy of a portrait of Deborah Kerr which was used in The Life and Death of Colonel Blimp in which Roger Livesey (The League's "Padre" Mycroft) also starred.
Forbes points out in his commentary on the DVD that in most films of the time Hyde's wife would be described as dead and not dismissed in such a manner. A scene in the script following the dinner party has Hyde, followed by Race, visiting a teenage girl at school—her photo is also on his desk. It is implied that she is his daughter. A scene which did not make the film has Weaver the teetotaler reaching for the brandy after Hyde has left the dinner. Lexy reminds him he shouldn't but Weaver drinks anyway.
In the original script, Race addressed others as "old dear".
Cary Grant was offered the part of Hyde but turned it down.
Queens Gate Place Mews, SW7, was used as the filming location for Edward Lexy's (Richard Attenborough's) garage.
The film was successful, being the sixth most popular movie at the UK box office in 1960. By 1971 it had earned a profit of £250,000 Over twenty years later Bryan Forbes estimated the profit as between £300,000 and £400,000.
The League of Gentlemen, was mentioned in the movie The Wrong Arm of the Law (1963) as one of the films that “Pearly Gates” (Peter Sellers) was going to show his gang of crooks as a part of his training program.
The film was included, along with three other Dearden films, as part of the box set Basil Dearden’s London Underground by the Criterion Collection.
In 2006, a restored version of the film was released as a special edition DVD in the UK. The extras include a South Bank Show documentary on Attenborough and a PDF version of Forbes' original script. An audio commentary for the film was provided by Forbes and his wife Nanette Newman who features in the film as Major Rutland-Smith's wife.
The book and film inspired both Alan Moore's comic series The League of Extraordinary Gentlemen and its spin-off movie, and the British comedy troupe The League of Gentlemen.