Welcome to Chelsea-by-the-sea

When Londoners decamp en masse year after year to a favourite resort, it can only mean one thing: local prices go up.

It takes more than a strong pound and wet weather to drive the regulars away from Cornwall. Whether they own or rent a place there, summer wouldn't be the same without the annual gathering of family and friends on a windy Cornish beach.

It takes more than a strong pound and wet weather to drive the regulars away from Cornwall. Whether they own or rent a place there, summer wouldn't be the same without the annual gathering of family and friends on a windy Cornish beach.

The hardy tend to avoid the prettier, gentler south coast and head for the north where the sport is surfing rather than sailing. Except in Rock, which, thanks to its position on the Camel estuary, has the best of both worlds and a particular cachet that gives it an edge over its neighbours.

Strangers become friends as they return year after year, and it has earned its reputation as a Chelsea-on-Sea because many people from the same part of London, even some from the same streets, end up holidaying together.

Since it could just as easily be Tunbridge Wells-on-Sea or Harrogate-on-Sea, what that really means is those who come from an affluent area - where property prices are high - are prepared to spend more just to be in Rock. A good 25 per cent, according to estate agents - and that in a village where 75 per cent of the properties are second homes.

Those who prefer to rent generally take the same house every year and come to regard it almost as their own. Alex Roads of John Bray and partners, estate agents and holiday lettings, says 15 years on the trot is not unusual. "Even their friends think they own it, and are quite surprised when they discover it is rented."

The most expensive high-season rent on its books at present is £1,500 a week for a new, six-bedroom house in a great location. Most family-house rents are between £800 and £950 a week, falling to £350 for a small flat without a view. During the summer this represents good returns for their owners.

"The problem is that there are very few good-size houses in Rock, with parking, views and within walking distance of the beach, but this is what everyone wants. The rest are mainly smaller properties between £150,000 and £300,000. Many of the best houses have been passed down through the family for generations. When people find what they want, they hang on to it,'' says Mr Roads.

Rock's greatest attraction is that, apart from the lovely beaches, watersports and golf, it has nothing for the day-tripper. If you want to eat chips on the harbour wall, then Padstow, across the estuary, is far more appealing.

It also has Rick Stein, of course. His famous fish restaurant followed by a bistro, delicatessen and cookery school have led to the fishing port being dubbed "Padstein". Even if he is the most compelling reason for an evening ferry trip to Padstow, not everyone who stays in Rock wishes to spend their waking moments trying to get a table in August.

Jane Ewing, who is new to Cornwall, says she didn't buy there to pay London restaurant prices. "We bought our house in Rock on a whim after a long lunch. We saw an advertisment for it and peered at it through a hole in the hedge. By the end of the week it was ours. Everything is within walking distance, including St Endoc golf course, which was one of our main reasons for buying there."

They also fell for the property because it was run-down but had the potential to be turned into a lovely house with a self-contained annexe. "A couple of years on it has turned out to be a much larger project than we ever imagined. It involved a lot of red tape and it is very easy to lose control of the job if you are not living there. We soon discovered that to keep popping down to Cornwall from London was nonsense, even with the new roads,'' adds Ms Ewing.

The notion that throwing money at a property is an easy way of getting exactly what is wanted is also nonsense. Planning is tightly controlled, says Rosina Shepherd of Jackie Stanley, the estate agents and Harbour Holidays letting company. Buyers need to do their homework before they get carried away with ambitious schemes, particularly if they include extensions.

"We have a waiting list of a least 100 people looking for a five-bedroom house with a sea view in the £500,000 price range and nothing suitable on the market at the moment," says Ms Shepherd. For £1.25m, though, they do have a 15th century farmhouse with estuary views in 13 acres that are rented out to an organic farmer.

Location is everything as far as the price is concerned and a million pound property right on the coast might well struggle to make £300,000 further inland. Anyone familiar with the area will know all the outstanding houses. When Knight Frank recently advertised a property near Port Isaac in Country Life, it had calls from all over the world. Many of the callers knew exactly which house it was.

In Trebetherick, which is at the heart of Betjeman country, no one could miss the Bodare hotel on the popular Daymer Bay. In need of refurbishment, it is about to go on the market with John Bray for £850,000 and is very likely to sell into the residential market.

New build is rare in Rock, but two miles out an upmarket holiday development at Roserrow golf and country club has been selling four-bedroom properties for around £300,000. All-weather tennis courts, a pool and a gymnasium take the misery out of wet summers. The agent, Jackie Stanley, is also selling new houses at Trebarwith Strand, renowned for its surfing beach, for prices ranging between £200,000 and £295,000.

More than a few people find themselves spending as much time in their second home as at their main address. The next step on for the families decamping to Cornwall for the whole summer, is the prospect of running a business from the South-west.

Graham King, who runs an advertising agency for local enterprises, had a cottage in Port Isaac before deciding to settle in an old farmhouse overlooking the Camel estuary. "We used to come down in the middle of winter so we knew it at its quietest time. There seemed no reason why we couldn't run our graphic design business just as easily from north Cornwall as Surbiton,'' he says. "I work intensely for a period, but when I stop I can be out in my boat fishing within minutes. It is glorious."

And when does a holidaymaker become a local? Perhaps when the pub and the petrol station stop charging a tourist rate, but more likely it is when they are included in the jokes about "emmits". Buying a home is not a passport to becoming Cornish, however pleasing the prospect may be.

Estate agents:

John Bray, 01208 863206;

Jackie Stanley, 01208 862424;

Cole Rayment & White, 01208 862299

Chartered building surveyors:

Richard Thomas Partnership, 01208 72991