FEARING the worst from British film comedies usually pays dividends. Your expectations are so low that it actually seems better than anticipated.

And so it turns out with Run, Fat Boy, Run which marks the big screen directorial debut of Friends star David Schwimmer.

He does a decent enough job - steady but unspectacular - with this rom-com about Dennis (Pegg, co-writer of the script) who does a runner on his wedding day, jilting his pregnant bride Libby (Newton) at the altar.

Five years later, Libby is set to marry her new boyfriend, an American go-getter (Azaria). To impress her and their son (Fenton), Dennis enters a marathon race.

This is not such a good idea for a flabby smoker who regards exercise as a sin.

His best friend (Moran) needs him to finish the race to pay off his gambling debts, his landlord (Patel) will evict him if he doesn't complete the course, and Dennis hopes succeeding will show Libby that he's not such a waste of space.

Run, Fat Boy, Run is not much of a belly laugh - apart from a pricking a giant blister sequence - but more of a gentle rib-tickler that gets enough smiles to make it worthwhile.

Schwimmer keeps things moving along swiftly enough, pausing only to focus his camera on London landmarks and the name of the race sponsor.

He's helped enormously by Pegg - and not just because he gave the originally US-set script an English makeover. Pegg shows he can handle being a movie leading man rather than just a TV funny man having a go at films.

Newton has a pretty thankless task as the girl he jilted, with Fenton's not-too-cute kid and Moran getting some of the biggest laughs.

Stars: Simon Pegg, Thandie Newton, Hank Azaria, Dylan Moran, Harish Patel, India de Beaufort, Matthew Fenton
Running time: 100 mins
Rating: Three stars