We're all nosy neighbours

With 27 monthly magazines on the subject and hundreds of hours of TV airtime a week, it's fair to say that looking around other people's houses is a popular pastime. Small wonder, then, that the capital has embraced the London Open House weekend concept with such vigour. For this is the through-the-keyhole opportunity of the year and is guaranteed to bring out the voyeur in all of us. Now a decade old, it has mushroomed from its modest North London beginnings into an annual sightseeing spectacular - indeed, it's the largest architectural event in Europe. More than 500 buildings across the capital, from Bexley to Wandsworth, are opening their doors for free to anyone who fancies a good snoop in the guise of being cultural.

A 'collective' of people, including the original mastermind and director of London Open House, Victoria Thornton, choose the properties and they are as likely to include a Seventies housing estate as the capital's grandest buildings. 'It doesn't have to be a great gem, it can be a little gem,' says Thornton, 'although we do employ an architectural standard.' In other words, whether you go behind the scenes at a brutalist tower block or a Georgian town house you should be seeing a good example of that particular architectural style.

Then there's the democratic nature of the weekend. Residents of less fashionable boroughs can look forward to the unusual spectacle of day trippers turning up to admire their fine period pieces and seminal social housing. But the biggest feel-good factor is that the weekend relies on goodwill - of the organisations and individuals who open their offices and homes and of the visitors who must resist the urge to snaffle an ashtray.

Far from being unwilling, those who open their doors to strangers have often approached the charity (occasionally, Thornton admits, she has to decline the offer on the grounds of, ahem, taste).

Andy Nettleton and Ia Hjarre are showing their family house near Borough Market for the first time this year. Both are architects and became involved in the scheme when a home they had designed in Bermondsey made it on to the shortlist.

Hjarre admits that it feels weird to be letting strangers into their home. 'Our house is low-budget and not very big,' she says. It's home to their children Max and Moa plus Millie the kitten and is a great example of how space can be adapted to accommodate a growing family. 'The event is great. It's like a mission to show people what you can do,' Hjarre says. 'I'm from Sweden and this all feels v ery un-English but then this city has a great mix of people and personalities.' She does admit, though, to a touch of nerves about whether people will like the way they have decorated and, yes, serious cleaning will take place beforehand.

Last year's tally of 350,000 visits over the weekend shows just how high the level of interest is. Thornton prefers not to use the word snooping - inquisitiveness is her term - but she does admit that London Open House enthusiasts come for many reasons. For hard-core architecture fans it's a chance to feast on their favourite vintage. 'Some people are interested in their local area,' Thornton says, 'while others choose buildings that interest them, such as the BBC offices or theatres.'

So what is it that fuels our interest in other people's spaces? Buckingham-based clinical psychologist, Dr Roy Bailey, believes this obsession has happened since society became more aspirational. 'We all think we're arbiters of taste,' he says. 'People generally fall into one of two camps when they look around properties. I call them optimisers and minimisers. Optimisers want to put a bit of what they see into their own

Where London Open House has scored is that it recognises our love of looking at both the grand and the domestic. While National Trust properties are riding high with almost seven million paying visitors in the past year (an annual rise of about 12 per cent), so are the new housing developments that attract hordes of serial showhouse viewers in search of a free day out. Then there are the eight million viewers of the UK Style channel who revel in wallto-wall coverage of big strong girls attacking the nation's scruffiest semis.

Homes magazines have seen the most startling growth, with 20 new titles having been launched since the start of the Nineties. 'We're curious about other people,' says Sue Rose, who edits Your Home magazine. 'The ten homes we feature in each issue satisfy the public's thirst for good decorating ideas.' But, like Dr Bailey, she believes that there is another secret pleasure in peeking at the way others live. 'For some people, it's also a chance to say, "Would you take a look at that?"