Peter O’Toole uses both his physical frailty and his undeniable charisma to exceptional effect in this small-scaled but incisive character study of an aging actor enchanted by an attractive but uncouth young woman. “Venus” is the name he gives her, and though Roger Michell’s film doesn’t have the ineffable beauty the title suggests, thanks to its star it possesses both a delicate charm and a poignancy that doesn’t descend into mawkishness.

O’Toole plays Maurice, a semi-retired thespian who still takes parts when he can find them (even if they require him to play a corpse) but spends most of his time chumming around with his old pals, fluttery Ian (Leslie Phillips) and rotund, soothing Donald (Richard Griffiths). Maurice may be suffering from prostate problems, but when he meets Jessie (Jodie Whittaker), the nineteen-year old grand-niece who’s descended upon Ian ostensibly to help out the old man but in reality to get a cheap place to crash while looking for a modeling job, he’s immediately smitten, even though she’s just a lower-class layabout. Poor Ian, who finds the girl’s very presence irritating, is pleased when Maurice offers to give him a respite by taking her on outings and securing her a stint as an art-class model (though his real desire is to watch while she poses).

The rest of the picture is really little more than a dance routine between the old rogue and the flirty but hardly interested young woman—a relationship that never goes very far beyond an absurd infatuation on the one side and a mercenary interest on the other. But gradually Jessie comes to feel something for Maurice—not a sexual interest, but almost a filial one. And in a way she does become a kind of Venus, transcending her rather grungy beginnings to grow into someone at least approaching the elevated if imaginary vision the old man has of her.

Interspersed with the Maurice-Jessie scenes are some delicious moments, including one in which Maurice and Ian have drinks at a men’s club before proceeding to a church where they survey the plaques commemorating the actors buried there, and another in which Maurice visits his ex-wife Valerie (Vanessa Redgrave). Though they spend only minutes together, the rapport between O’Toole and Redgrave is marvelous, suggesting in a brief compass a long, lived-in relationship.

But while all the others work splendidly against him, it’s O’Toole who carries the picture, savoring every witty line and florid moment provided him by Hanif Kureishi’s slight but well-crafted script. Under Michell’s loose direction, he’s given free rein but holds back skillfully, never allowing the character to descend into overripe extravagance.

“Venus” is a modest picture, marked by strictly utilitarian production values and cinematography by Haris Zambarloukos that’s utterly straightforward and occasionally positively dull. But O’Toole lights up the screen with such masterful understatement that he makes the film graceful and elegant. Watching him reminds you of what Pauline Kael wrote of James Mason in his last role, in “The Shooting Party” (1984): “His face and, especially, that plangent voice are so deeply familiar that when we see him in a role that does him justice there’s something like an outpouring of love from the audience to the man on the screen. His performance validates our feelings.” It’s an observation that fits this occasion as perfectly as it did that one.