If it is mandatory that Hollywood make nothing but remakes and sequels — and this appears to be the case — you could do worse than choosing 1981’s “Arthur” for an upgrade. Well-remembered for Dudley Moore and John Gielgud’s droll performances, it’s a good but not great trifle with a premise that’s easily adapted for another performer: a wealthy drunk playboy engaged to a fellow socialite whom he doesn’t love meets the woman of his dreams. Russell Brand does the same sort of wild-living hedonist routine that Moore did (though he does it taller); the original isn’t an untouchable classic; heck, why not?

That’s basically how the remake — with Brand as Arthur and Helen Mirren in the Gielgud role of his valet/caretaker — has turned out: Heck, why not? Complain all you want that Russell Brand is no Dudley Moore (and you’ll get no argument here), but the lanky, skeletal comic can deliver a dry, exceptionally British line of dialogue with the best of them. The dialogue he’s given to work with by screenwriter Peter Baynham, who has written for subversive British comics Steve Coogan and Sacha Baron Cohen, isn’t always stellar, and the story is as dully conventional and trite as it was 30 years ago. But Brand and Mirren attack it with gusto, handing in near-perfect performances like the old pros they are. There’s no more reason to rush out and see it than there was for anyone to make it, but since the opportunity has presented itself — heck, why not?

Brand’s character, Arthur Bach, is heir to a billion-dollar fortune who spends his days and nights drinking, dressing up as Batman, carousing through New York, and generally living the high life. In all things he is supervised by Hobson (Mirren), his nanny since childhood and surrogate mother. His actual mother, Vivienne (Geraldine James), disapproves of his nonsense and threatens to cut him off from the money if he won’t marry Susan Johnson (Jennifer Garner), who comes from a wealthy family and can reassure investors that the Bach empire is in good hands. This is, in Arthur’s words, “a macabre conspiracy to inveigle me into a loveless marriage” — a good example of the eloquently humorous turns of phrase at which the film occasionally excels.

The plan is disrupted when Arthur meets Naomi (indie darling Greta Gerwig), an underemployed Brooklyn girl who — that’s right — is free-spirited and pixie-ish. (I’m pleased the movie doesn’t overdo this cliche, since Arthur is pretty laid-back himself.) He’d rather be with Naomi but will lose all his money if he does. It’s not like he can get a job, though he does try this, briefly, with predictably disastrous results.

The degree to which you find all of this entertaining will depend on how much you are generally fond of Brand, no question about that. But I give him credit for at least attempting to create a real character here, rather than just playing himself. Arthur is spoiled, but he’s big-hearted, and you can’t blame him for trying to solve every problem with money, not when it’s the only thing he’s ever been taught. Brand is amply supported — perhaps even overshadowed — by the ever-delightful Helen Mirren, a seasoned veteran who cares not one whit that the part she’s playing has been played before. She helps us see that for as frustrated as Hobson is with her exasperating charge, she genuinely loves the big moron. And can anyone tell a drunk party animal “Your safari into the pointless ends now” with more grace and authority than Helen Mirren?

As Naomi, Gerwig interacts well with her more famous costars. What could easily have been the Arthur & Hobson show — stand back and admire their hilarity! — is instead more inclusive; Naomi gets some good punchlines, too. Sadly, that’s about as far as the sharing of wealth goes. The amusing Luis Guzman is wasted as Arthur’s chauffeur, a dumb guy in a movie with no place for dumb guys; Nick Nolte is given nothing sensible to do as Susan’s brash, self-made-millionaire father; and Jennifer Garner has the thankless role of Arthur’s cartoonishly bottom-line-minded fiancee. The scene in which Susan shows up drunk at Arthur’s penthouse is nonsensical in the context of the story, and more than a little embarrassing for Garner, who doesn’t play that type of loosy-goosy stuff well.

This could be the kind of movie that gets remade every generation or so, plugging whoever the current Russell Brand type is into the lead and updating the details. This generation’s “Arthur” certainly won’t be as beloved as the last generation’s, but it’s no disservice, either. With a handful of solid laughs and a modicum of snappy dialogue, it’s liable to amuse, if not overwhelm, an audience seeking casual, forgettable entertainment.

B- (1 hr., 50 min.; PG-13, a little profanity, a little vulgarity and mild sexuality, nonstop drinking.)