Top brains devise formula to put an end to 'hedge rage'

After decades of torment in the shadow of freakish, fast-growing conifers, angry householders have a new weapon to set alongside the chainsaw. All it takes is a bit of squinting and a few clicks on a calculator.

Government scientists have published an official hedge-trimming formula which means that, armed with no more than a stick and basic maths, the sufferers can calculate exactly how much of next-door's foliage should be chopped back.

Their main target will inevitably be the most popular hedging plant, Cupressocyparis leylandii, the scourge of the suburbs. Millions have been sold since the Seventies, when the plant won favour for its hardy temperament, elegant shape and prodigious growth of a metre a year. But the Leyland cypress is almost solely responsible for terms such as "hedge rage". It has plunged living-rooms into darkness, blighted gardens, and set thousands of neighbours at each other's throats.

Perhaps naively, ministers hope that new guidelines will see an end to such unpleasantness, encouraging householders to "settle matters with their neighbours amicably".

Drawn up by the government's Building Research Establishment, the guidelines set out a maximum hedge height – "H" – at which trees are judged acceptable and do not block out light. They involve measuring the distance between a window and the hedge, halving the result and adding one metre. If the actual height is more than this figure, the hedge is too high.

The BRE has even included a diagram of how householders can estimate the height of giant trees using only a hand-held stick or ruler. Nothing under three metres is affected.

But according to Michael Jones, the founder of the campaign group Hedgeline, the battles will continue for a while yet. Mr Jones, a pensioner from Selly Oak, Birmingham, spent 20 years in and out of court attempting to force his neighbour Charles Stanton to trim his 35ft Leylandii hedge, and the costs topped £100,000 by the time he was able to claim victory.

Hedgeline now has 4,000 angry members, their complaints ranging from subsidence to psychological bullying. Mr Jones points out that the guidelines, while welcome, have no legal power. The Regeneration minister, Sally Keeble, has promised that they will form the basis of new legislation, but no one knows when. The last attempt to outlaw giant hedges, a private member's Bill, ran out of time after filibustering by Conservative MPs.

"We feel we're being fobbed off," said Mr Jones. "It's a small step forward, but the guidelines still allow very high hedges. They only affect the most extreme cases. If the guidelines are allowed to become the basis of a new law, they will still allow bullying neighbours to intimidate those around them."

There is a similar view from the other side of the horticultural fence. "You need a degree in maths to work out these guidelines. The Government has fudged it again," said Chris Pagett, of the Association of British Conifer Growers.

He has further bad news for Leylandii haters. Despite its reputation, the species remains so popular that growers are now short of trees to sell.

According to Ian Richardson, director of Johnsons of Whixley Nurseries, the largest wholesale nursery in the UK, the adverse publicity has only driven sales higher. "All the controversy about them means that, while 10 per cent of the buying public have said these big, ugly trees are a menace, the other 90 per cent have said that's just what they're looking for. So we're selling 35 per cent more Leylandii than 10 years ago. Sales have really boomed in the past three years."