Location London

Nick Daubney, who has been a location manager in London for 20 years (his work has included two Harry Potters, and he is currently employed on Charlie and the Chocolate Factory), reckons it "used to be easier, because people were more laid-back. It's got much tighter now."

The Knight Bus scene in the latest Potter film was especially difficult, he says, because of its high-speed dash through central London. "We could only stop the traffic for four minutes and we had this scene where the bus did a 360-degree spin. We mounted it on a turntable, choreographed people to walk in slow motion so the bus would look faster - and then, in the end, it got cut ..."

Daubney believes the city will continue to be difficult until the Road Traffic Act - which currently allows roads to be closed only for special events (such as parades) and "statutory undertakers" (basically, repairs on gas and water pipes) - is amended to allow filming. "Unless that changes, you can never be certain, because every police constable has the right to decide whether or not you can film on the day," he says.

Not surprisingly, the police like to play it safe. Currently, the police solicitor has advised that, were an incident to occur while traffic had been stopped for filming - the result, say, of some herbert in a BMW deciding to drive through anyway - the police would be on shaky legal ground.

All this is gradually changing, however, following the launch in April of Film London, an organisation described - in appropriately Livingstonian language - as "the new strategic agency for filming in the capital".

"We know London can be a difficult place," admits FL chief executive Adrian Wootton, "but the productions keep coming back. After all, what amounts to 10,000 days of filming a year is not inconsiderable." It helps that the newly re-elected Mayor is pushing for a change in the Road Traffic Act. "Post-April," says Wootton, "we've really been motoring."

The city has, of course, been a movie star since filming began - think Hitchcock's Sabotage, Ealing's Passport to Pimlico, Antonioni's swinging London epic Blow-Up, Bob Hoskins in The Long Good Friday - so it's about time it got its act together.

First there are the tourists, one in five of whom come to England because they saw us on a film or on television. (Bridget Jones: The Edge of Reason, due out in America at Thanksgiving, is liable to fill half a dozen jumbos alone.)

Tourists apart, filming generates an estimated £1.6 billion annually for the capital, so the economic argument is pretty compelling.

Mind you, the idea of films doing London's PR job for the city and its attractions can be a little double-edged. As often as not, a location will be used to represent somewhere else. The romantic comedy Wimbledon (opening here in September) could only have been shot at Wimbledon - with some scenes actually filmed during last year's championship - but others are less site-specific. The film 101 Dalmatians was shot in the Tower of London, but only because there is a row of houses there that make a perfect London street without the traffic hassle. And Hampstead Heath did a nice line in rural Connecticut for the upcoming Kevin Costner movie, The Upside of Anger.

THERE are, of course, some no-nos. It's all very well if you want to show everyone drifting round a pristine, picture-postcard London in, say, Love, Actually. But if you want to show the grungier side of the city, you may find it more difficult. London Underground won't allow pickpocketing scenes. The Port of London Authority will turn down any applications involving suicide leaps from bridges. Historic Royal Palaces rejected Johnny English because of its disrespect for things historic and royal. And the carriages in Mira Nair's Thackeray adaptation, Vanity Fair (out early next year), played havoc with the historic garden pathways at Hampton Court.

While Thunderbirds finally got the go-ahead to use Tower Bridge, the London Eye, which places great emphasis on safety, emphatically nixed another potential Thunderbirds scene where the wheel would have toppled into the Thames.

And the same attraction also told Kevin Allen, director of Agent Cody Banks 2: Destination London, released earlier this year, that he couldn't make lastminute changes to what had been agreed, reportedly causing Allen to moon at the Eye's representatives from a high-flying capsule.

But in general the city is willing, says Sue Hayes, London Film Commissioner (now part of Film London), provided you plan things properly.

"For Thunderbirds, we organised a massive meeting of all the key agencies. The director [Jonathan Frakes] made a presentation and said, in effect, 'This is what we would like to do, London.' And London responded. Everybody was up for it."