Jon Kay BBC West of England correspondent

The reason is simple: more and more people are choosing to live on the canal - so, there's sometimes little room left.

It's easy to see the attraction: waking up in the morning, surrounded by beautiful countryside, with woodpeckers in the trees and deer grazing on the tow-path.

But there's another, more practical reason, why the canals are filling up: high property prices in areas like Bath are persuading locals to turn their backs on bricks and mortar and enjoy a cheaper life on the water.

It's the same situation in other parts of Britain.

Sam and her two-year-old son are typical. "It's just gorgeous," she says. "There's no way we could buy a flat in Bath, so this is the best alternative. You're at one with Mother Nature. It's brilliant."

Sam does have a licence for her narrow-boat and says she abides by the rules set by British Waterways - moving her 70ft-long vessel every fortnight.

But some boat-dwellers are not so law-abiding. A growing number of them are refusing to buy licences and refusing to move.

You're at one with Mother Nature. It's brilliant Sam, boat owner

"They're squatting!" say James and Joyce Edmonds, holiday-makers from the Midlands.

"They're not paying to be here, so they shouldn't be allowed to use the facilities. And the state of some of the boats is terrible! They've got peeling paint, and rubbish everywhere - they look like piles of junk."

The situation has led British Waterways to clamp down. In the past it admits that it has been quite relaxed about the regulations.

Narrow boats have been left for weeks without being told to move-on - even in the most popular locations.

But now, according to the posters along the tow-path, boat-owners are told to keep moving to the next "locality" - and they will be fined �25 for every day they stay in one place beyond the two-week limit.

Eugene Baston from BW says the reason is simple: "If we had a bigger canal network, perhaps there would be more room for everyone, but we've only got 2,000 miles of water and that means there's limited space. And the number of boats is increasing every year."

They're squatting! And the state of some of the boats is terrible! They look like piles of junk. James and Joyce Edmonds, holiday-makers

But some dwellers are incensed by new regulations. They claim that having to move their vessels every fortnight will make boat-owning so difficult that many people will be forced back onto dry land.

"They're putting holiday-makers before the permanent residents," says Sam.

"They just want to get us to buy permanent moorings, but that would cost me �2,000 a year - and there's no way I can afford it."

Critics say the move could be so annoying for dwellers, it could threaten the centuries-old tradition of people living on our canals.