Sunday might get the rain, but one senses that it’s cloudy just about every day in Robert Hamer’s 1947 variation on London’s East End. As depicted in the brooding “It Always Rains on Sunday,” which begins a one-week engagement at Film Forum on Friday, the Bethnal Green community is its own dark world, lacking money but overflowing with gossip, built atop a foundation of bitterness, envy, and despair.

That this slice-of-life melodrama collides with a fugitive-on-the-run thriller makes “Sunday” a most notable installment of 1940s British cinema. But it’s when things go from gray to pitch black in the film’s final moments, building to a climax that links the anguish of a prison inmate with the daily routine of a working-class wife, that “Sunday'” delivers an existential wallop for the ages.

Sunday, of course, is the day of rest in this insular neighborhood, and the film’s title — a line of dialogue uttered in dismay by one of the central characters — suggests that even the gods have it in for Rose (Googie Withers) and her neighbors, throwing down foul weather on their single day off. Not that anyone in the city much believes in God or His wrath for their sinful behavior — and not that Rose gets much rest from her lengthy list of daily chores.

Indeed, she’s annoyed from her very first gesture. Awaking next to husband George (Edward Chapman), a pleasant but dreadfully dull chap, Rose pounds on the wall, signaling to her two stepdaughters — the overly sweet Doris (Patricia Plunkett) and the aspiring seductress Vi (Susan Shaw) — to go downstairs and prepare tea for their father. It’s an opening scene steeped in routine and slathered in passive aggression.

It isn’t until later that we learn that George and his girls represent Rose’s life by default. But the man who had been her Plan A, as it turns out, just snuck himself into the bomb shelter in the back yard. Rose’s first love, Tommy (Jack McCallum), has escaped from prison and returned, cold, dirty, and in need of help. After the family leaves for the day, Rose cooks him food, cleans his clothes, and puts him to sleep on her bed.

As the day unfolds, Tommy’s hiding place upstairs turns this everyday home into a powder keg. Hamer, who would go on to direct the chilly 1949 comedy “Kind Hearts and Coronets” and the 1959 murder mystery “The Scapegoat,” prolongs the claustrophobia and the familial tension. Rose plays the part of the dutiful housewife, all the while remaining trapped downstairs by a family that won’t let her climb into bed with the man she has always loved.

Rose is the central figure in this tragedy, but Hamer is quick to take the camera outside as well, offering a neighborhood that is poisoned to the core. We watch as married men pursue young Vi out on the town, looking for any escape from their wives. We watch as three small-time crooks fail to off-load something as benign as a crate of stolen roller skates before finally locating a buyer — a crooked priest. Only Lou (John Slater) seems to get the score, always smirking, always scheming, the suit with the thick wallet who fixes boxing matches and flirts with Vi. He’s more crooked — and more revered — than any other person living in this circle of postwar hell.

Upon its release in 1947, “It Always Rains on Sunday” marked a turning point for British filmmaking, shifting the attention in such melodramas away from the agony of the elite and toward the struggles of the everyman. (Indeed, as Film Forum notes on its Web site, the film was atypical for Ealing Studios, which was home to familiar cozy British comedies, but saw its first success with Hamer’s film.) In “Sunday,” more than one character opts to cash out and attempts to end his life.

The title may point to the weather, but it’s clear by the time Tommy makes his final, frantic dash from the police through a moonlit train yard that, even if Sundays were sunny — even if lost loves could be reunited — little hope resides in the houses lining this boulevard of broken dreams.

ssnyder@nysun.com