When you live in a holiday resort like Marbella, you get used to watching an endless stream of holidaymakers with the last-day blues, solemnly wheeling their suitcases past the swimming pool, taking in a last view of the sea, before embarking on that dreaded journey to the airport.

"I hate this moment," sighs Mary Foster from Bristol as she hauls her bags out of her seaview apartment on Marbella's Golden Mile. "It's always such a horrible feeling having to leave all of this," she says, wistfully casting an eye across the palm trees.

Mary only has six weeks to go though before she comes back again. Apart from other obvious benefits such as being able to escape when the black skies of August at home look disturbingly like winter, owning a bolthole in Spain is a great way to avoid that awful final-day-of-holiday feeling that you'll never return.

Along with some 600,000 British buyers so far, with a further half a million predicted to do so in the next five years - Mary has bought a holiday home in Spain which she visits several times a year, sometimes for as long as six weeks each time, and with different combinations of friends, offspring, grandchildren or on her own.

"We can get here so cheaply and easily on low-cost flights that we can come out here regularly," says Mary. "And each time we come we bump into lots of people we know who are doing the same thing, so you end up with a whole new set of friends in a different country."

Shaun Powell, managing director of Lighthouse, a company which finds holiday homes for foreign buyers by working with a network of ethical estate agents in Spain, comments: "In the past, we went en masse to Spain to spend our annual cheap fortnight in the sun. Now we are still going there in equally large numbers but as home-owners not package tourists. "Spain is by far the number one destination for British second-home buyers," Powell adds, "and two thirds of them choose to buy on the Costa del Sol or Costa Blanca because these coasts have an excellent year-round climate, good infrastructure and established expat communities."

Sometimes, however, a lack of local knowledge and expertise in buying property in a country with a different culture, language and legal system can see buyers falling foul of disreputable agents, developers or negligent lawyers for whom sudden price changes, selling illegal properties or promising unrealistic returns on off-plan investments are daily practices.

This is why Lighthouse was set up, to provide its customers with a protected environment in which they can be reassured that they are dealing only with trustworthy parties.

"Our network of 100 agents currently spans the Costa del Sol and Costa Blanca, with Almeria, Mallorca and Costa de La Luz to follow," says Shaun Powell.

"All of our member agents must work according to the network's strictly-enforced code of ethics, rules and regulations. If they don't, they are expelled from the network, which is highly damaging to their business, and there is an arbitration process to resolve matters for the customer," Powell adds.

Holiday homes need not only be by the beach, of course. Lighthouse has a database of nearly 10,000 properties, which range from rustic 30,000-euro ruins to 15-million euro villas, and many customers express an interest in buying an inland property in need of renovation.

Tom