The Black Sheep of Whitehall

Jessop offers Davis a job mainly to get him out of his office and stop him from causing trouble. Davis arrives at Whitehall demanding help with his mounting debts, and Jessop, his only former student who succeeded, invents a job opportunity on the spot to placate him. The plan backfires when the situation spirals beyond his control.

Earlier, Davis is described as debt-ridden and forced to vacate his correspondence school office, establishing his desperation.

Jessop leaves to fetch the real Professor Davys from the railway station, but while he's away, Davis is mistakenly introduced to BBC interviewers as the famous economist. With no actual expertise, Davis improvises absurd answers about gambling and con tricks, leading to mounting confusion until the actual professor arrives.

The timeline sets up that Jessop must leave Davis alone at the Ministry, creating the opportunity for the mix-up.

Professor Davys is a leading economist who has returned from South America to brief the British government on a vital trade treaty intended to bolster Britain's war effort. The treaty represents a crucial economic lifeline during World War II, which is why Nazi agents are determined to prevent it from being signed.

The timeline establishes Davys as a key economic adviser whose expertise could shape Britain's wartime survival.

Crabtree is a fifth columnist working for Nazi Germany who poses as Professor Davys to infiltrate the British government. He is part of a conspiracy to prevent the trade treaty from being signed by impersonating the real economist and intercepting classified information. When Jessop discovers the deception, the stakes shift from comic misunderstanding to genuine espionage.

The timeline notes that Jessop discovers the man he brought is Crabtree, a fifth columnist, raising the threat level significantly.

After Crabtree's true identity is revealed, Jessop realizes he needs Davis's help because the real Professor Davys is being held in a safe house by Crabtree's associates. The pair form an alliance where Jessop promises Davis a real job at Whitehall in exchange for his assistance in tracking down the missing economist and preventing the Nazi plot from succeeding.

The timeline establishes that Jessop promises Davis employment in exchange for helping locate the real Davys.

Davis and Jessop adopt various disguises as they chase leads across London, using quick-change tricks to move through different locations without raising suspicion. The disguises allow them to navigate through a web of stations, offices, and shadowy corners while evading Crabtree's network of conspirators.

The timeline specifically notes the use of disguises and quick-change tricks as the pair pursue their mission.

The film concludes with Davis and Jessop successfully locating the real Professor Davys and thwarting Crabtree's conspiracy before the trade treaty can be compromised. Their improvisational skills and courage, though initially thin on confidence, prove enough to outwit the Nazi agents. The happy ending sees the villains thwarted and the economic lifeline for Britain's war effort secured.

The narrative builds toward a finale that blends wit with bravery, as established in the meta notes about the film balancing farce with genuine stakes.

The BBC interview scene becomes chaotic because Davis, having no actual economic expertise, fumbles through the questions using gambling metaphors, con tricks, and outright wrong answers. The interviewers grow increasingly incredulous while Sir John, the government minister, watches his calm facade crack under the strain. This scene serves as the comedic centerpiece where the farcical deception reaches its peak before the stakes turn serious.

The timeline explicitly identifies this as the moment where the ruse unfolds and creates mounting disbelief.

The rapid-fire disguise sequences are a hallmark of the film's farcical style, typical of 1940s British comedy-thrillers. Each disguise represents Davis and Jessop attempting to infiltrate different parts of Crabtree's network, with the visual humor coming from the absurd speed of their transformations. This device advances the plot while maintaining the light tone that distinguishes the film from genuine spy thrillers.

The meta notes emphasize that the film maintains a consistently light tone with the disguise trope serving both plot and comedic purposes.

By the film's conclusion, Crabtree and his network of fifth columnists are successfully outmaneuvered by Davis and Jessop. The conspirators are thwarted, and the plot to compromise the trade treaty is defeated. The ending follows classic comedy structure with the villains caught and the heroes successful, though the film leaves the specific fate of Crabtree somewhat ambiguous in typical farcical fashion.

The meta notes confirm the film ends with heroes successful and villains thwarted in classic comedy tradition.