Thanks largely to currency movements, British owners in the most popular countries for holiday homes - namely France, Spain, Portugal, Italy and the US - saw a surge in the value of their bricks and mortar in 18 months to December 2009.

Figures from Close Treasury, a subsidiary of merchant bank Close Brothers, suggest the total value of British-owned homes in these five countries was £42 billion at the end of last year.

The 98,000 British owners in France, for instance, saw their property prices fall by around 6.6 per cent in the period under review.

But any owners who sold up in France and converted their money back into sterling still showed a profit, thanks to the 13.2 per cent rise in the value of the euro against sterling.

The US dollar rose by 16 per cent against sterling, achieving the same effect for property owners returning to the UK.

There are 25,500 British owners in the US and they saw the value of their home increase by an average £1,752, again because of currencies working in their favour.

In Spain, where 144,500 Brits have a home, property prices fell by around 8.3 per cent in 2008/9 - but the rise in the value of the euro against sterling produced a collective gain of £1.1 billion, or £7,700 per property.

In Italy, with 8,500 British owners, a combination of rising property prices and a strong euro meant the average value of a British-owned home rose by an average of nearly £25,600 each.

Mark Taylor at Close Treasure says: "Many expect recent volatility in the currency markets to continue, and this is having a huge impact on the value of homes abroad held by British people.

"If you bought a property in the eurozone when the sterling exchange rate was in the $1.50s, and sold it now with the pound down to just over $1, you could get quite a good return."

The average home in Italy has seen its sterling value rise by over 65 per cent since mid-2005, largely because the euro soared by 27 per cent against the pound during this period, when Italian property prices rose by about 30 per cent.

In the last year alone, a UK investor in Italy could have made a return of more than 10 per cent, despite an increase in local property prices of only three per cent.

However, owners of homes abroad could come off worst from expected currency trends in 2010.

There is a widespread perception the euro is seriously overvalued, and a sharp correction in its value against sterling could sink some of the present 'paper' gains for lucky Britons.

Mr Taylor said: "If you haven't sold already, it might be sensible to wait a little while, until things settle down again after the General Election.

"If there was a hung parliament and sterling weakened, the case for selling up to secure a profit would be strengthened. If sterling strengthens, then British property sellers abroad will bring less back to this country from a sale."