How to make pounds 400,000 without even moving

A couple have made pounds 400,000 buying and selling a house in London in a matter of months - without ever having moved into the property.

The speed with which they have made such vast profits is the clearest evidence yet that house prices are not only rising but a boom is under way.

The property, in Chelsea, was bought last year for pounds 590,000. The couple have just sold it for pounds 990,000. In Hanover Terrace, Regent's Park, one couple stand to gain a similar sum from selling a property for pounds 3m after buying it for pounds 2.6m four months ago.

Charles Barclay, of estate agents Knight Frank, said: "Our statistics point to a rise in price in prime London residential property of over 17.5 per cent over the last 12 months."

The return of profiteering through housebuying, not seen at such levels since the late-Eighties property boom, is not the exclusive territory of the rich. Middle-class buyers have also discovered a new means of making money in the booming property market - turning homes into "house futures". The homeowners-turned-speculators are buying up houses from builders even before a brick has been laid, in the belief that prices will rise so fast they will make a profit by the time construction is complete.

A combination of social and economic factors is fuelling the boom, particularly in the area within the M25 London orbital motorway. The bonuses of City professionals, foreign buyers, consumer confidence, pent-up demand, a severe shortage of homes for sale, building society share windfalls, higher earnings growth, and income tax cuts next month have all contributed to higher prices. Concerns about interest rates after a possible change of government are countered by a belief that property is a good investment when inflation rises.

Last week the Nationwide Building Society reported a 9.7 per cent increase in average UK house prices last year - the highest annual change since 1989 - but in the south the rise this year already looks set to be substantially higher.

Builders are attracting buyers who are snapping up homes as soon as a builder has advertised his proposals, and are agreeing a price based just on a builder's plan. Mike Dobner, regional sales director of Fairclough Homes, said: "People are buying houses when we haven't even laid the foundations, assuming that they will rise in price constantly. We have been setting our prices at a level we think they will reach by the end of this year and people are quite prepared to pay them, thinking values will go up even more.

"People are behaving as if they are trading in housing futures."

Evidence from one of Fairclough's own developments suggests the speculators may well be right. Riverside houses built by the firm in Kingston-upon- Thames, Surrey, were on sale for pounds 245,000 in February; now they cost pounds 295,000. In London and the Home Counties, the price rises are highest in "golden postcodes" - the latest estate agent jargon for the most desirable neighbourhoods.

Andrew Scott, a director of the London residential department of agents Lane Fox, said: "For the perfect property - freehold, in the best neighbourhood, with a garden, off-street parking, with no nearby commercial premises - you are talking about prices rising by about 25 per cent."

"It can't go on like this," said another agent. "It's not real life is it? Although, of course, it is real money."