Many of us recoil at the thought of our parents doing it–the specific intimacies they share in their bed. As a result, we’ve built a mental firewall between their sexuality and that of everyone else. But Paula, a 30-something woman in the new British drama The Mother, doesn’t have the luxury of denying the reality of her mother’s sexual desires, for a very plain reason: Her recently widowed Mum is getting it on with Paula’s boyfriend. But The Mother isn’t some sort of Cockney-accented Jerry Springer episode. Instead, we’re squarely in the tradition of middle-class English realism, the humble soil that Mike Leigh tilled so successfully in the 1990s with films like Life is Sweet, Naked and Secrets & Lies. Here the director is Roger Michell, director of not-so-good films like the overwrought Changing Lanes and the trivial Notting Hill; on the bright side, he directed Persuasion, the best of the Jane Austen movies. But along with a cast of actors with similarly mixed resumes, Michell has done a career-best job with The Mother.

Based on a script by Hanif Kureishi (author of the celebrated novel The Buddha of Suburbia and the screenplay of My Beautiful Laundrette), The Mother certainly has a sensationalistic hook. But the real agenda isn’t to celebrate or deplore the sex that May, the title character, gets from a stud half her age; rather, it’s about a woman of a pre-feminist era who, now that her life is nearly over, fears that she’s never actually lived it. But, as this gentle and nuanced film stresses, living a life fully always has a cost, and in The Mother, it is the daughter who pays the toll.

When we first meet May, she and her husband Toots are traveling to London for an apparently unusual visit to son Bobby, daughter Paula and their respective families. But the visit is ill-starred from the get-go. Toots is visibly ailing, and it’s a struggle for him to keep up with his wife as they navigate the perils of modern London. When they arrive at their son’s doorstep, their daughter-in-law greets them with a look of irritation. The grandkids barely acknowledge them, and their businessman son blows through on his way back to the office. Their daughter Paula, an emotionally fragile would-be writer, joins them for an uneasy dinner, and later that night, Toots expires of a heart attack.

All of this occurs in the first 20 minutes or so, and the rest of the film is given over to May’s grieving, which she refuses to do discreetly, out of sight of her children. Deciding to stay on in London, she crashes with her daughter and soon takes an interest in Paula’s boyfriend Darren, a carpenter who is building an addition to Bobby’s house. Darren is, of course, much too young for May, but they strike up an easy acquaintance.

Although May initially finds Darren coarse, she warms up to his artistic and emotional sensitivity. He seems to be the only one who appreciates his loneliness. In one early scene, he muses, “I imagine people getting less frightened as they get older, getting better at dealing with things.” When May allows that this could be so, he replies with a rueful smile, “Something to look forward to.”

As played by Daniel Craig, Darren is the classic sexy carpenter, an easygoing, artistically-inclined but deeply troubled man. He’s the kind of man who passively slips into affairs with emotionally clinging women while telling himself he’s simply a victim of their needs. (Craig, like director Michell, has an erratic resume: While he was spot-on as the brooding poetic destroyer Ted Hughes in Sylvia, he gave possibly the worst performance of the decade as Paul Newman’s idiotic psycho son in Road to Perdition.)

Still, the movie ultimately belongs to Anne Reid, a veteran actress of no particular screen repute who, although nearing 70, could easily pass for a woman 15 years younger. Reid gives a marvelous performance as a woman who essentially skipped the middle decades of her life, thanks to her controlling husband and her own passiveness. Interestingly, in her short, doughty carriage, she bears a passing resemblance to the German actress Brigitte Mira, who starred in Fassbinder’s Fear Eats the Soul, the most famous movie to deal with the topic of an older woman in love with a young man. The Mother isn’t as good as that film, but Reid matches Mira in her determination to find lasting love–in defiance of social taboos–late in her life.

If The Mother lacks the stature of Ali: Fear Eats the Soul, with its truly harrowing exploration of loneliness, racism and social ostracism, the new film nonetheless deserves credit for not sentimentalizing May’s plight. There’s an acute sense that she is no better and no worse than her troubled children. Once May becomes Darren’s lover, she becomes giddy and girl-like, turning into a not-entirely sympathetic subscriber to the notion that all is fair in love and war.