Open House London 2012

Victoria Thornton, a confessed "buildings-aholic", founded Open House at her kitchen table in 1992, aged "30-something", and this year she was awarded an OBE for her work.

In 20 years, this city-wide annual event has gained a phenomenal following and this month (September 22-23) it expects to attract more than 300,000 curious Londoners, often queuing, keen to get a look at other people's homes.

'It's not a tourist thing it's for Londoners. People love it. They get to explore the city and to think about it.'

Her first event had only 20 buildings on the list. Now, 750 places take part, of which 100 are residential. There is also every kind of public building, from a pumping station to the Gherkin (which had queues a mile long when it first showed). Before you ask, the Shard, not quite ready yet for such an onslaught, has signed up for next year.

And Open House is now global — 25 other countries run their own version and, as long as they are free, not-for profit and maintain quality, they are allowed to use the name.

In 1992, Thornton, a writer who lives with her architect husband in an Edwardian mansion block on the edge of Hampstead Heath, had just published a guide to London architecture, painfully aware there wasn't much good contemporary architecture in London and the subject wasn't taught in schools. "But," she says, eyes alight, "if we aren't taught, if we aren't informed about it, how can we join the debate, argue for something better?"

The best way to learn, she says, is to visit good buildings. Thornton explains that she gave Open House its name to make architecture feel available to everyone. Her ambition was to help Londoners learn to love their city in the easiest, most fun way possible. "It's not a tourist thing," she says firmly. "It's for Londoners."

This intelligent, laid-back approach has paid dividend after dividend. The event has no Government funding but is funded by individuals, local authorities and other bodies.

"People love it. They get to explore their city, and to think about it. If you have a horrible environment, it reflects on you," she says. "I won't say that architecture changes lives, but it impacts on them. We should demand more from our environment. There's no reason to accept things as they are, we should try to make them better. Good architecture isn't a mathematical equation; it's more than that; and we all recognise it when we see it."

There is a lot more housing in today's Open House. Thornton says we demand more from the design of our homes now. Increased knowledge and awareness have played a big part: we know more, so we want more. "In a home, we look at the spatial qualities, and the light, and the materials, which are so important," she says.

Looking back over the past 20 years, Thornton is modest about her own undoubted achievement, congratulating other bodies, such as the Heritage Lottery Fund, for helping revitalise the city. "We all care more about public space, the bits between buildings. But it takes time to regenerate a city. The big surprise is how green buildings have become, how architects are now designing that in as a norm."

Next year she launches the Archikids Festival so parents and children can have fun exploring and learning together. "Open eyes, open minds, open doors," she says. "That has always been our motto."

Oh, and what was the building that once didn't want to be involved? "Ah," says Thornton, beaming, "that was the Bank of England."

Open House London 2012 runs from September 22-23. For full details, visit londonopenhouse.org

Victoria Thornton's new book, Open House London, looking in depth at 100 buildings, is just out from Ebury Press at £25. Readers can get a copy for the special price of £22, including p&p, by calling 01206 255800, quoting Homes & Property.