Summer (15): Robert Carlyle is a working class hero. Not in the bitter sense in which John Lennon, with his fur coats and Manhattan apartments, sang about such a breed, but in an admirable, uplifting way.

Dir: Kenny Glenaan
With: Robert Carlyle, Rachael Blake, Steve Evets
Star rating: ***

Robert Carlyle is a working class hero. Not in the bitter sense in which John Lennon, with his fur coats and Manhattan apartments, sang about such a breed, but in an admirable, uplifting way. He won the title for life in Ken Loach's Riff-Raff when, as Stevie the labourer, he was memorably asked if his grim existence ever got him down. "Depressions are for the middle classes," Stevie batted back, "the rest of us have got an early start in the morning."

Carlyle is back on brilliant, working class hero form in Summer, Kenny Glenaan's Sheffield-set drama about sunlit childhoods and chilly middle age. The film, which won a clutch of Scottish Baftas, is a commendable enough, three-star affair, but Carlyle's performance merits four. After a run of roles which could best be described as critical hits with his accountant and no-one else, the kid from Maryhill is back in the picture.

With its council estate setting, bleak plot, and humour that limps straight from the gallows, Summer feels at first glance like vintage Ken Loach. The veteran British director's production company, Sixteen Films, is indeed one of the picture's many backers. So far, so grim up north, and that might put some off. Audiences aren't exactly short of doom and gloom at the moment. That said, Glenaan and his leading man take these unpromising circumstances and mine some golden screen moments from them.

The opening is one of them. Shaun (Carlyle) and his ailing pal Daz (Steve Evets) are having a day out in the country, which in their case means the Derbyshire hills surrounding the estate. It's a glorious day, the best global warming has to offer. When Shaun and Daz were children, playing in the fields and woods alongside their pal Katy, holes in the ozone layer were nowt but a twinkle in Al Gore's eye. As the weeks pass and Daz's health deteriorates, Shaun thinks increasingly of those days, and one summer in particular.

With Daz fading fast, Shaun decides to make contact again with Katy (Rachael Blake), his first love. Though she doesn't live far across town, her world is a universe away from Shaun's. Intelligence, plus conscientious, encouraging parents - a mum and a dad, fancy - took her away to university and a career as a solicitor. As the frequent flashbacks make clear, Shaun and Daz didn't have the same advantages, or chose not to take the meagre ones on offer.

It's a familiar story, and the fact that Shaun is Scottish brings on a bad case of the deja vus. At first, as we see the youngster and his weary mum - does anyone do "pinched and fretting" quite so movingly as Kate Dickie? - battling the system, it's tempting to see this as just another reprise of an old, sad song: stunted hopes, lives half lived, children not being given the help they need and sheer bad luck.

Glenaan's picture doesn't have anything new to offer on that score, but what he is saying is worth repeating, and he delivers the message in a heartfelt, sometimes heartbreaking, way. Glenaan engineers several inspired moments, among them the teenage Shaun passing his younger self in the school corridor, each boy glancing at the other with a mixture of affection and fear.

Glenaan's smartest decision is never to let the camera stray too far from Carlyle. There are other notable performances here, by Evets and the younger Shauns especially, but this is Carlyle's film. Physically, the Trainspotting and 28 Weeks Later star is such a tiny figure on screen, but he is wired for sound, fury, and intense emotion of every kind. The Shaun you see one moment tenderly washing his disabled friend and lifting him into bed, is the same one that minutes later is exploding with rage in the back garden, his character doing to a poor, innocent Wheelie bin what he'd like to do to life in general.

Again, you could say we've seen this noble class warrior act in various guises before from Carlyle. Yet to complain about him being a one-note actor would be like saying Scorsese has made one too many gangster pictures, or Jimmy Stewart's nice guy persona grew same-old, same-old after a while. There's nothing wrong, and a lot right, with having a niche. Carlyle is never going to be Hugh Grant, and thank Notting Hill for that. At his best, as he in Summer, he is a brutally honest, hugely affecting performer who brings an uncommon dignity to difficult characters. As a working class hero, on this form, he'll do for me.