After Mrs Merton and the legendary Royle Family anything written by Caroline Aherne deserves my attention. So I had high hopes for The Fattest Man in Britain, which airs on ITV this Sunday, December 20th, 9pm-11pm. And while I wasn't entirely disappointed by this watchable and well performed drama, it's not really in the same league as some of her previous work.

Featuring a superb Timothy Spall as Georgie Goodwin, it's a touching tale with some nice music from Badly Drawn Boy. Remember him with that silly hat he used to wear. Set in Rochdale and inspired by an ITV documentary a few years back, Georgie is without doubt one hell of a fat man! Obvious questions arise such as how did they get that Timothy Spall to look that fat - did they get the fat suits from Little Britain? And just how does he go to toilet?

But what's striking about Georgie is just how different he is. With a high pitched voice and an almost obsessive need to appear clean and well groomed he's nothing like the stereotype of the bluff, fat man who cares nothing about his appearance that many of us have.

His size, it turns out, is caused by the psychological effect his mother dying 23 years ago - a need to eat to take the pain of her death away - and he hasn't left the house since. Instead he makes a living from being a kind of circus act for very stereotypical foreigners (they look like they are are straight off the set of 1970s sitcom, Mind Your Language). These curious, camera-toting foreigners are delivered to the house by taxi driver cum agent Morris Morrissey who claims he is taking them to see 'The Eighth Wonder of the World'.

As ever, with Aherne's work there's shades of light and dark in this drama. There are genuinely funny bits, most of them provided by Bobby Ball who is excellent as the aggressive but sometimes clueless agent, not least when he asks for a black Latte and then tries to conduct high level negotiations with another agent with his milky moustache.

But there are really touching scenes too, including one where Georgie and Amy - the pregnant gardener who Georgie has taken under his wing to protect from an abusive boyfriend - are lying on the floor singing Moon River. Indeed it's very reminiscent of the scene in The Royle Family where Jim and pregnant daughter Denise are lying on the bathroom floor waiting for the ambulance.

On the whole this engaging comedy drama is definitely worth watching, but if you are expecting the subtlety of The Royle Family you may be disappointed. The storyline is predictable and straight out of Hollywood.