But Oadby and Wigston borough council, in Leicestershire, has had even more dramatic success against illegally posted notices by simply spending £240 and getting a local printer to produce 1,200 posters of its own. It's a fiendishly simple idea. Armed with large orange neon "Cancelled" stickers, council cleansing staff have taken the guerrilla flyposting war to the illegal advertisers. Wherever they see an illegal notice for a car boot sale, rave, concert or furniture sale, they slap a "cancelled" sticker on top.

Oadby and Wigston has had amazing results. Graham Norman, the head of client services and contracts at the council, says that, before the campaign started, cleansing staff were removing 70 to 100 illegal posters per week. Eight weeks after the initiative was introduced, just after Christmas last year, this was reduced to zero. Norman says: "It's one of those things that you think: 'Why hasn't someone done this before?' The worst thing you can do to a flyposter is tell the world that the thing they were advertising is not going to happen."

The council produced its own sticker with "cancelled" in very large print. But, after taking advice from its own legal department, it added in very small print along the bottom of the sticker, a note explaining: "This poster has been cancelled by Oadby and Wigston borough council."

And to add to the sense of satisfaction that the campaign brings, Norman says the illegal flyposters, anxious not to let the public think that their event has been cancelled, even oblige by taking down the "amended" posters. "One of the main reasons for the success of the scheme is that it has the potential to hit the profit margins of the companies putting them up," he says.

But hasn't the campaign caused roars of anguish from local businesses? "We haven't heard any feedback from local businesses because flyposting is illegal and flyposters don't want you to be able to trace the business that is actually paying them," Norman says.

Street cleaning staff say that they are happy to be given a new weapon. "Apart from anything else, it reduces the amount of work they have to do," Norman says. "We leave our 'cancelled' poster up for 24 hours, but the flyposters usually take them down before then, so we are getting them to do our work for us as well."

Norman does not claim ownership of the idea. He says that it came out of a brainstorming session looking at ideas for cracking down on illegal advertising across the borough. A number of officers decided to look at this element of the wider problem of dealing with litter on private land.

They set up a group made up of staff from planning, environmental health and legal services, contracts management, streets cleansing and performance, plus the mayor and the chair of the environment committee. The initiative received extra publicity when its results were written up in the Year of Delivery Book produced by the Improvement and Development Agency - an umbrella group that helps local authorities to share ideas and innovations.

Since this publicity, the idea has been taken up in Northampton, Wellingborough, Leicester and Rotherham. And it is being assessed by Bedford town council and Birmingham and Liverpool city councils.

Cleaning up after flyposters costs local authorities thousands of pounds every year. Camden council spent £250,000 removing illegal ads last year, and it decided to apply for the Asbo against Sony and BMG chief executives after it received more than 1,000 complaints from residents. Last week, Camden's applications for Asbos against Sony chiefs Catherine Davies and Jo Headland were withdrawn after the company promised not to commission further flyposters.

However, Camden says it still intends to take Asbo action against BMG. And it says other councils, including neighbouring Islington and, further afield, in Hastings and Greater Manchester, have expressed an interest in using Asbos.

But Norman argues that it's easier and cheaper to avoid legal entanglements with high-powered lawyers from the music world. He says: "We don't consider it necessary when you can use something as simple and effective as a 'cancelled' sign."

· Oadby & Wigston council is at www.oadby-wigston.gov.uk

· The Improvement and Development Agency is at www.idea.gov.uk

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