Airport plan 'will shatter peace of Thames palaces'

It argues that near-constant plane noise would disturb visitors to "national treasures" such as Kew Gardens and Hampton Court Palace if the number of flights increased by more than 50 per cent.

Richmond Park, Barnes Wetland Centre and Syon House are also at risk as they are directly under existing or proposed flight paths and face planes flying overhead every 90 seconds.

The report was published by Thames Landscape Strategy, whose patron is Sir David Attenborough andwhich aims to conserve the historic parks and gardens clustered along the Thames between Kew and Hampton.

Director Jason Debney said: "The proposed expansion of Heathrow would have a devastating impact on how we enjoy these riverside open spaces, including some of the UK's most visited tourist attractions.

"Short of issuing everyone with ear muffs as they near the Thames, how can we mitigate against constant and deafening plane noise?"

Ham House - the best-preserved 17thcentury house in Britain - Marble Hill House, Bushy Park, Strawberry Hill House, Hampton Court Palace and towpaths and smaller parks enjoyed by millions of visitors each year are also at risk.

Consultation on plans to expand Heathrow ended last week and an unprecedented 18,000 people lodged objections.

Sue Runyard ofKew Gardens, a World Heritage Site, said: "We have learned to live with the current noise levels but we have great concerns, not just about the expansion but about the possibility of no runway alternation."

At present, alternating the use of the runways means half the gardens are overflown for half the day and the other half for the rest of the day.

"That's a very valuable situation and we want to preserve it," said Ms Runyard. "Using both flightpaths would mean planes flying over both the north and south of the gardens at the same time."

But a Heathrow spokeswoman claimed the expansion would actually reduce aircraft noise at the Thames attractions.

She said: "The Government has said that Heathrow's expansion will only go ahead if there is no more noise overall than in 2002. Aircraft are getting quieter and it is likely that Kew Gardens, Hampton Court and Richmond Park would all have less aircraft noise than today if a third runway went ahead."