In “Vera Drake” Mike Leigh plays the propagandist, offering us a defense of legal abortion by trotting out the idea of the saintly abortionist pioneered by John Irving in “The Cider House Rules.” But he does so with incomparably superior results.

In fact, so complete and persuasive is the portrait he paints of working class north London in 1950, when hardly anyone would have supported making abortion legal, that he under mines his own point. Everything about the film – apart from the propaganda – is done so well that the propaganda strikes a jarring note and looks out of place.

In this world everything, from the tightly belted trench coats worn by all the men to their seemingly glued down “wave” hairstyles so popular in the period, seems part of a vast collective effort to bolt the lid down on some very significant parts of life and keep them well out of sight.

Here everyone has a secret, from Sid (Daniel Mays), the black-marketeering son of Vera (Imelda Staunton) and Stanley Drake (Phil Davis) to Susan (Sally Hawkins), the upper-class girl who, date raped and impregnated, seeks both the imprimatur of the medical profession on her “operation” and to keep it hidden from her parents. For this she has to pay 50 times what the working-class girls of the back alleys of north London have to pay for Vera’s services.

Vera herself doesn’t charge. She performs abortions for free, in the same spirit she shows by looking after her aged mother and visiting neighbors in need of assistance. It is her friend Lily (Ruth Sheen) who puts her in touch with the girls “in trouble” and, without Vera’s knowledge, pockets the two guineas (L2.10 in the decimal currency) she charges them.

Mr. Leigh does not really mind the illegality of abortion so much as these secrets, this hidden-away world that the gloomy, rationed, buttoned up, “repressed” society of postwar Britain still believed had to be kept out of sight.

Throughout the film, for example, hardly anyone can bear to say the word “abortion.” Even the women who have one, even the judge and the police try to avoid it. When Vera is arrested she begs the police inspector (Peter Wight) not to tell her family, and one of the film’s most moving scenes comes when they have to be told and the inspector allows Vera to do it herself. But she cannot speak the word out loud and has to whisper it in Stan’s ear.

Mr. Leigh has a fine eye for such small touches – like the need to keep internal doors shut in the tiny, unheated, warren-like houses of the working class in order to conserve heat, a habit which he makes into yet another metaphor for the compartmentalized moral world they live in.

Yet the post-1960s notion of being “uptight” is very far from being adequate to describe these peoples lack of spontaneity and expressiveness. The more we see of their up closed society the more we are inclined, I think, to respect it. Mr. Leigh obviously understands what a mistake it would be to have Stan, even in defending his beloved wife, suddenly turn into a spokesman for the permissive consensus of our own time.

Ms. Staunton gives a tremendous, Oscar-worthy performance in the title role, but equally good are Alex Kelly, who plays her daughter Ethyl, and Eddie Marsan as Ethyl’s suitor, Reg. Both are young people, still in their 20s, but seem at least as old as Stan and Vera. They have a stunned look, as if they have seen far too much of life – Reg, like Stan, is a veteran of the war – and now devote their energies to keeping their emotions tightly in check.

My favorite moment comes as taciturn Reg stands up at the gloomy family feast just before Vera’s trial and says: “This is the best Christmas I have had in a long time. Thanks, Vera; smashing.” The beauty of his remark is that we are impressed not only by its unexpected kindness and tact but also by the fact that it is probably true!

The propagandist in Mr. Leigh may want us to dismiss as worthless the culture keeping Vera and Stan and Ethyl and Reg the desperately repressed people they are, but the filmmaker in him has done too good a job of drawing their characters – which, after all, are inescapably the product of their society – for us to think of them and love them as other than they are.

And that means loving them for their contradictions. The only person in the film who attempts any defense of the law is poor Sid, the young tailor who offers women’s nylons in exchange for cigarettes to his mates who are courting. Never having questioned the uses to which those nylons are put, Sid nevertheless confidently blames his mother: “It’s wrong, isn’t it?” he says tearfully to his father. “It’s little babies. It’s dirty.”

Stan doesn’t answer directly. Instead he says: “You can forgive her, Sid. She’s your mum. She’d forgive you anything, wouldn’t she?” Later he remarks: “Everything’s black and white for Sid. He’s young.”

Like everyone else in this time and place, Stan too assumes that abortion is wrong and dirty. He tells Sid he would have put a stop to it if Vera had told him what she was doing. But this world of repression and disguise that both fascinates and appalls Mr. Leigh also leaves room for compassion for those who do wrong – which may be the wiser course than trying to make wrong right, as we have done since their time.