George, 10th Duke of Bristol, and his friend Richard Halton are poverty-stricken members of the British upper class, George having squandered his money on women (as he tells the film's narrator). They attend a party at George's own London home, let to the young, wealthy and attractive American Helen Hale. At the soiree, George is rude to Maria Wislack, a rich widow with whom he is acquainted. Richard is genuinely in love with Maria, but will not tell her so due to his poverty. Meanwhile, George is oblivious to the fact that Helen is in love with him, and finds the thought of marriage distasteful. Maria grows tired of waiting for Richard to make his feelings known and proposes that they spend a month together as man and wife in Scotland "on approval" to see how they get along (although he will have to sleep in a hotel). George, much to their mutual discomfort, invites himself along. They are soon joined by Helen.
The unexpected arrival of additional - and unmarried - guests disturbs Mrs McCosh, Maria's housekeeper, and she soon departs, taking with her all of the household servants. The two couples are left to fend for themselves. Richard does his best to please the demanding Maria, though Helen privately advises him to tell her to "go to hell". George, in the meantime, loafs and does nothing to help out.
At the end of three weeks, Maria tells Richard that she is willing to marry him and even to settle £5000 a year on him, but when he discovers that what he had thought was a test of his patience turns out to be the way she behaves normally, he turns her down. At the same time, George decides he loves Helen and asks her to marry him. She would have been happy to accept his proposal three weeks before, but after becoming better acquainted with him, she gently turns him down. She eventually begins having second thoughts, however, and she and Richard set about making the others jealous and leave the island together for the hotel on the mainland. As it turns out, George and Maria have the same idea.
Eventually, both Helen and Richard have nightmares about their loved ones, together alone in Maria's house, and speed back there. When Richard climbs up to Maria's bedroom window, she is frightened by the (to her) unknown intruder and rushes to George's room. There is where Helen and Richard find them together. Recriminations soon follow.
The film then flashes forward to Helen, who is showing the family photo album to her two sons. The narrator addresses her as Lady Bristol, only to be corrected by her. She has married Richard, while George, to the narrator's disbelief, is Maria's partner.
Clive Brook took this popular play (originally set in the early 1920s) and placed it in the late Victorian era, where the concept would've been much more shocking. Brook wrote the screenplay (keeping very close to the original play), produced and directed the film. It's one of the very few films featuring Beatrice Lillie, often referred to as "The funniest woman in the world" for her eccentric personality and portrayals in so many amusing stage plays and revues.
The film begins with an amusing documentary-style prologue about contemporary life in 1942 England, which serves to introduce Brook's character, George, in the late Victorian era.
Filmmaker Lindsay Anderson called the film "the funniest British light comedy ever made" (according to the DVD box).
On Approval was the "dark horse" of the 2014 edition of the Turner Classic Movies Film Festival. The first screening of On Approval, held at the TCL Chinese Theatre in Hollywood on the first full day of the festival, was a sell-out prompting a second showing at the Chinese on the final day of the festival (which also sold out). The two screenings were introduced by film historian Jeffrey Vance, who also recorded an audio commentary track for the Blu-ray edition of the film.