It is mainly faithful to the novel, omitting some minor incidents.
The film follows the adventures and misadventures of Edward Henry (Denry) Machin, an ambitious young man from a poor background.
Denry cheats at an examination in order to qualify for entry to a 'school for the sons of gentlemen'. At the age of 16, he becomes a junior clerk to Mr. Duncalf, the town clerk and a solicitor. He meets the charming and socially well-connected Countess of Chell, a client of Duncalf's, and is given the job of sending out invitations to a grand municipal ball. He 'invites' himself, and wins a five-pound bet that he will dance with the Countess. This earns him the reputation of a "card" (a "character", someone able to set tongues wagging) – a reputation he is determined to cement. But the next day, Duncalf angrily sacks Denry.
Denry offers his services as a rent collector to a dissatisfied former client of Duncalf's, Mrs Codleyn. His reputation as an efficient and no-nonsense collector brings the business of Mr Calvert. But Denry quickly realises that he can make more money by advancing loans, at a highly profitable interest rate, to the many tenants who are in arrears. He also discovers that Ruth Earp, the dancing teacher who is attracted to Denry, is herself heavily in debt. Despite this, he and Ruth become engaged.
While on holiday in Llandudno with Ruth and her friend Nellie Cotterill (as chaperone), he witnesses a shipwreck and the rescue of the sailors—an event that he turns to his financial advantage. He also realises Ruth's spendthrift nature, and they part on bitter terms.
Denry starts up the Five Towns Universal Thrift Club, a bold venture that allows members to purchase goods on credit. This increases Denry's wealth and reputation, and he is able to expand further, thanks to the patronage of the Countess.
Denry's social ambitions expand. He becomes a town councillor, and he purchases the rights to locally born Callear, the "greatest centre forward in England", for the failing local football club.
Ruth reappears, now the widow of a rich, older, titled man. He considers renewing their relationship but is unsure of his (and her) feelings.
Nellie's father, a builder, is bankrupt (again), and the family decide to migrate to Canada, with Denry's assistance. As they are boarding the ocean liner at Liverpool, Denry realises that Nellie is devastated at her potential loss and that he really loves only her. Ruth, who is also present, is furious, but quickly starts a fresh relationship with another older titled gentleman.
Nellie and Denry marry. Denry becomes the youngest mayor in the history of Bursley.Alec Guinness as Denry Machin
Valerie Hobson as Countess of Chell
Petula Clark as Nellie Cotterill
Glynis Johns as Ruth Earp
Edward Chapman as Herbert Duncalf
Veronica Turleigh as Mrs Machin
Joan Hickson as Mrs Codleyn
George Devine as Herbert Calvert
Wilfrid Hyde-White as Lord at Liverpool dock (uncredited)
For Guinness, playing the romantic lead was a departure from his previously comic roles. The film was one of the first adult screen roles for Clark, who received her first screen kiss.
The New York Times critic Bosley Crowther gave the film a mixed review, writing "the script Eric Ambler has adapted from Arnold Bennett's old novel, 'The Card,' is provokingly uninfested with dramatic compulsion or push. It just ambles along very gently from one situation to the next ... 'The Promoter,' while vastly amusing in spots, is not a first-rate Guinness show."
It was largely filmed in Burslem in Stoke-on-Trent, the basis for the fictional location of Bursley, and in Llandudno, North Wales.
Clark recorded a vocal version of the film's theme, with lyrics by her long-term accompanist, Joe "Mr Piano" Henderson.