Alfred Enoch and Ian McKellen in “The Critic.” Sean Gleason/Greenwich Entertainment

At 85, Ian McKellen doesn’t have many performances left in him, so any movie that lets the actor carve ham with such exuberant relish as “The Critic” is worth his time and ours. Anand Tucker’s British drama isn’t great art, but it is a good time, one that darkens steadily and satisfyingly as it goes.

Among other things, the movie represents a playwright’s revenge – and probably a director’s, actor’s, cinematographer’s and key grip’s – against the parasites of the press in the aisle seats: the critics waiting to dash to the nearest bar as soon as the curtain drops and wield their pens as scalpels, drawing the blood on which they feed. The critic in “The Critic” is probably most people’s idea of the species, an arrogant fop convinced of his own importance, delighted by his own wit, and refusing to stoop to a two-syllable word when six or seven will do. Speaking as the maligned party, we’re not all Anton Ego – well, most of us aren’t – but McKellen has great fun enlivening the cliché with details and flourishes of business.

His character, Jimmy Erskine, is the chief theater critic for the Chronicle, a right-of-center broadsheet in late 1930s London. Long-established and legendary, especially in his own mind, Jimmy can make or break a show or career, and lately he’s taken delight in tormenting Nina Land (Gemma Arterton), an actress of some talent but not a lot. “The vamping and shrieking Miss Nina Land [has] all the grace of a startled mule,” runs one Erskine review of a recent Jacobean tragedy. “Her death is akin to a deflated dirigible.”

“The Critic” takes a turn for the complicated when the Chronicle’s owner, a Murdochian press baron, dies and is replaced by his son, Viscount David Brooke (Mark Strong), an honorable if dull sort under whose aristocratic crust can be glimpsed a deeply lonely man. The new boss sets out to clear the newsroom staff of deadwood, and after Jimmy is arrested for a drunken carouse with his young secretary/lover (Alfred Enoch) – homosexual acts between men were illegal in Britain until 1967 – he looks to be next on the chopping block.

Ian McKellen and Gemma Arterton in “The Critic.” Sean Gleason/Greenwich Entertainment

Far be it from me to spoil how the critic retains his job, but it’s not altogether cricket, and it leads Jimmy into amoral and even immoral waters, not that he needs much of a push. The screenplay is by Patrick Marber, whose prizewinning 1997 play “Closer” is an even more devastating piece of emotional bloodletting – that one is great art – and he’s written McKellen a marvelous villain to play, airy and convinced of his own superior intellect until it’s much too late in the game to back down.

Arterton grants the part of the actress a bittersweet self-awareness of her diminishing fortunes – Nina is in her 30s and nearing the expiration of her ingenue status – and her own lack of scruples. Strong’s character, rather surprisingly, turns out to be the movie’s most affecting, a man with great passions inside him that are throttled by class. One of the best if least heralded actors of his generation, Strong turns in a performance that’s all the more heartbreaking for its subtle flickers of vulnerability.

McKellen is not here for subtlety, thank goodness. Both his performance and “The Critic” as a whole are shot through with the pleasures of overripe self-regard. Jimmy has a gift for disemboweling a production in a few words (“Hold your breath as you pass the Duke’s Theatre, for here is untreated theatrical sewage”), but he also sees himself as the last upholder of artistic truth, and not incorrectly. “You have to trust that we are present to you,” he tells Nina when she comes to him for advice, “sensitive to your deepest sufferings, your gentlest feelings, your most intimate thoughts. But you must trust that we can perceive all this without your help.”

Less is more, to coin a phrase. Ironically, under Tucker’s able direction, more is more: “The Critic” has been filmed in opulent tones of prewar amber, with rich attention to production design, score, costume, casting and performance. The movie hides its stilettos under velvet until the final scenes, when they come out and cause more damage than even the filmmakers seem prepared for. Revenge is a dish best served cold, but it’s the warmth of McKellen’s Jimmy Erskine – the egotism that propels the man happily forward – that keeps “The Critic” from freezing over.

Ty Burr is the author of the movie recommendation newsletter Ty Burr’s Watch List at www.tyburrswatchlist.com.