Try to forget Neil Maskell’s turn as a young Winston Churchill on TV’s “Peaky Blinders.” Put Winston out of your mind.

As “Bull,” every time the hulking Maskell enters a room people look alarmed. Shocked even. And nobody’s ever glad to see him.

‘Allo, Cheryl,” he says to his ex in the film’s opening scene. She’s crying, slack-jawed, at the sight of her current husband, duct-taped from head to foot in his easy chair. She barely has time to process this and dodge Bull’s query about someone else’s whereabouts, when he pitilessly and purposefully pokes that taped-face husband in the gut with a knife.

Because there is just one name Bull is dropping other names to track down, and that’s of the son “they” took from him.

“AIDAN!” he bellows at every single victim. They remain a victim only long enough for a flashback to tell us something awful happened years before, a travel trailer fire, a hasty burial in an open field.

These aren’t “victims” Bull is having his way with. They’re co-conspirators. His mission is nailing down what happened to his little boy, and butchering every single SOB who did him wrong, which only partly explains what they’re all so shocked and awed at seeing him.

Writer-director Paul Thomas Williams (the choral dramedy “Unfinished Song” was his) has produced an instant gem of the “vengeance picture” genre, with Maskell a sort of insensate brute bulling through the china shop that once was his life in the underworld.

The story is as jarringly violent as it is overly familiar. He starts on this spree. He’s working his way up to the “boss” (venerable character actor David Hayman). And as he passes through the way-stations of his past, embodied in former colleagues, relatives and acquaintances who are about to become bodies, flashbacks tell us what happened to Bull and show us the lad (Henri Charles) he lost, a loss he’s about to collect on, with interest.

Bull is a magnificently malevolent creation, on the page and in the flesh. He’s got no qualms about getting the drop on this villain or that one, even the one taking his kids to school. Kids are curious, and Bull is just as sweet at describing himself as you’d expect, given the slaughter we’ve already witnessed.

“Ooo’re you,” the children want to know?

“Aye’m the big bad WOLF!”

Williams gives us just enough of this suburban underworld, just a single corrupt cop, the merest hint of the “stuff” this Cockney mob and its branches are into. British underworld pictures are a bracing break from North American ones, largely because the violence is more personal. Fewer guns. We get a hint of why Bull doesn’t use them from the one time he has to acquire a pistol. It’s not at easy as in the U.S.

The best vengeance pictures never experience mission creep. Everybody confronted by this guy is shaking in his or her boots for reasons too obvious at the moment, and more obvious in an unnecessarily twisty finale.

“If you don’t tell me what happened to Aidan, I’m gonna make you EAT that little knife yer’oldin’, mate!”

I wasn’t nuts about the coda here. But even that can’t be faulted as it makes sense, dramatically.

Hayman makes a perfectly logical, absolutely sociopathic crime lord, a man as quick with a sawed-off as Bull is with a fist or blade.

Everybody else? They’re just china, here for Bull to smash through on his way to his ultimate destination — vengeance or death, or both.

Rating: R for strong violence, language throughout and some drug material

Cast: Neil Maskell, Lois Brabin-Blatt, Elizabeth Counsell, Jason Milligan and David Hayman

Credits: Scripted and directed by Paul Andrew Williams. A Saban Films release.

Running time: 1:28