The laugh-a-minute working class world of Rab C Nesbitt gets the left-wing Loach approach in this clash of family loyalty and morality.

Fifteen-year-old Liam (Compston) wants things to be just right for his former heroin addict mother when she's released from prison.

But instead of a paper round or even a Saturday morning supermarket job, he opts to sell knock-off tabs around the local boozers.

Then, after failing to go along with his mum's new boyfriend's scag-for-the-lags scheme, he finds himself with nowhere to live.

Hooking up with best pal Pinball (Ruane), the pair nick the heroin stash and start touting it around the local users in their Scottish sink estate.

Liam's entrepreneurial approach comes to the attention of a local gangster who admires his nous and he's soon in the firm - but will things work out as planned?

OK, so it's not a bag of laughs (pretty much business as usual for Loach), but the natural performances of all concerned make for compelling viewing.

Compston, a professional footballer, is heartachingly good as the youngster whose potential (he's got a thing for astrology) is mired in the all-consuming world of crime.

If you actually take time out to think about what's he's doing you should, by rights, be on the phone to Crimestoppers.

But such is the honesty of Liam's blind desire to look after his vulnerable mum that you find yourself preaching forgiveness.

Entertainment is not quite the word for films documenting the desperate straits of those trapped in Britain's underclass.

But at least they've got a film-maker with the talent to bring their world - without sleight of camera - to the cinema for all to see.

Tim Evans