Millions of viewers saw Lindley mum Carolanne Keith throw an almighty strop on Channel 4's Wife Swap programme last night. JENNY PARKIN wonders, why did she volunteer in the first place?

NOTHING defines a British family more than whether they have bikes, and ride them.

You could draw a big sociological chalk line between those who cycle and those who don't.

The Canns, of Devon, do. But the Keiths, of Huddersfield, don't.

Unlike the pie-and-mash loving couch potato Keiths, the bike-obsessed Canns tick all the right boxes for the health police desperately trying to get the UK eating broccoli and exercising properly.

What wasn't explored, though, was the potential long-term psychological damage of calling their kids strange cowboy yee-hah names Bow-Jango, Capability-Jack, Haby-Blu and Calamity-Jane.

A sort of overzealous über-family, they clearly looked down their suntanned noses at their new "mum", Carolanne Keith, of Wellington Street, Lindley, who huffed, puffed and swore her way through a bike ride, and displayed a deep dislike of fresh air and the countryside.

The 35-year-old eBay trading addict responded by locking away the bicycles and forcing everyone to enjoy themselves at a car boot sale.

More usefully, she gave their filthy house a good clean - they're usually far too busy doing exciting outdoor things to clear up.

Back in Huddersfield, Carolanne's adorable daughter Alice, nine, - usually left to play her trumpet alone and entertain herself in her attic bedroom - took excitedly to Ian's wife-for- a-fortnight Sam, who organised fun things like baking bread and an evening bike ride picnic to Longwood Edge.

Ian was less enthusiastic about swapping four wheels for two, as Sam rode with him to work alongside heavy traffic on Brighouse Road, Ainley Top.

Ignoring the predictable parp of brass band music every time there was a panning shot of the Keiths' terraced home, it was great, compulsive viewing.

Participants take the experience so seriously, with all the crying, soul-searching and self-righteous sounding-off, the desperation to cling on to their usual routines. So why do they volunteer in the first place?

At the end of the show, as usual, came the pointless summit in which each couple tries to persuade the other to be more like them.

"Open your eyes," Carolanne told the Canns. "To what? Boot sales and markets?" asked Sam, justifiably.

"To the world," said Carolanne, somewhat vaguely.

Of course what each clan could benefit from would be quick, simple lessons about (a) moderation, and (b) variety, in family life.

Unfortunately neither was in a position to enlighten the other.

But then, if they were, and if there'd been no shouting and stropping, where would the entertainment value have been?