A £3.3MILLION project to increase enjoyment of public spaces and historic palaces will be put at risk if Heathrow is expanded, it is feared.

The Thames Landscape Strategy - known as the Arcadia project - was put in place 10 years ago with the backing of conservationists including Sir David Attenborough, its patron.

But in a recent report, its director Jason Debney said: "The proposed expansion of Heathrow would have a devastating impact on how we enjoy our riverside open spaces, including some of the UK's most visited attractions."

Landmarks such as Kew Gardens, Richmond Park, Syon House, Chiswick House and Strawberry Hill House in Twickenham are renowned as places of tranquillity.

But Mr Debney says this is now going to become a thing of the past if extra flights go ahead.

Protesters against the greater use of Heathrow are already worried about pollution and disturbed sleep.

But this is the first time the Arcadia project has joined the ranks opposing Heathrow's plans to take more flights.

Syon House's head gardener, landscapes expert Topher Martyn, said: "Already what should be a peaceful refuge is an ear-shattering place to be.

"The planes on some days go straight over my roof.

"Not only do I wake up with the noise, I think the pleasure of visiting all the historic places round the Thames can be diminished."

Consultation on plans to expand Heathrow ended last week and a staggering number of 18,000 people registered protests.

At present rules to make aircraft take off from alternate runways gives at least half a day of peace and quiet in some areas.

But campaigners worry the scrapping of runway alternation would mean no respite in areas of attractive houses and parks.

Heathrow bosses say that quieter aircraft in the future will keep noise levels down.

However, Mr Debney is convinced the numerous plans to improve views and encourage access around Hounslow, Richmond and Kingston will now be undermined.

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