The value proposition for The Card is simple: Alec Guinness, Glynis Johns, light British comedy = you will enjoy.
It's based on a beloved Arnold Bennett story of the Five Towns, about life in a small industrial town in England at the end of the 19th century. Alec Guiness plays Edward Henry Machin, known to all as Denry. He's the son of a widowed washerwoman, bright, likable, ambitious and willing to cut corners. He wiggles his way into a job as a clerk, where he invites himself to the duchess' ball. Since he doesn't know how to dance, he visits Glynis Johns' studio.
Johns is most wonderful in her first scene. She still has the Voice, and looks lovely, but she is more than a bit of a snob and a hustler. She plays it a bit like Elsa Lanchester, all breeding and grasp. It would seem that she is Denry's perfect match, but his ambition is generous, where everyone wins (and he takes a cut), while she is only out for himself.
The movie isn't full of jokes and pratfalls. The humor is based on gentle observations of human nature. Although it's class-based humor, there is no class warfare. Guinness is loved by all from the butcher's boy to the bank owner. The old guard grumble, but they do admire his push.
Frankly, without Guiness' charm, this movie would probably be impossible.