The third runway at Heathrow will see a 30 per cent increase of 7,500 night flights a year over south west London, figures have shown.

Between 11pm and 7am, residents will have to endure 96 flights a night by 2030 instead of the current 75.

BAA, the owner of Heathrow, disclosed the increase of 27,300 to 35,000 a year to the Civil Aviation Authority in documents obtained by the Sunday Times.

The increase will affect even larger swathes of London, as the flightpath leading to the third runway will also cover Chiswick, Hammersmith and Kensington, which were previously unaffected by the noise.

As many as 260 flights a day will come in via the new flightpath.

Meanwhile Boris Johnson, the London Mayor, accused the Government of not having the "nerve" to let MPs vote on the expansion plans.

On BBC One's Andrew Marr show the Mayor said: "They haven't got the guts to call a Parliamentary vote on this matter."

The Tory Mayor, who has pledged £15,000 in public money to back a legal challenge to the plans, favours plans for a runway to be built on an island in the Thames Estuary.

He said Douglas Oakervee, the engineer behind Hong Kong's international airport island, would investigate whether this could be done.

However, the Mayor admitted that it was a "bit of a longshot".

Geoff Hoon, the transport secretary who announced the third runway on Thursday, again defended the plans in an interview with Sky News.

By allowing limited expansion, the government managed to reconcile the "inexorable" demand for more travel with its environmental commitments, he said. "I am pleased about the decision that we have reached because I do believe it is the right way forward for the UK."

On Saturday a “flash mob” of about 400 campaigners, organised via social networking sites, protested against the expansion at Heathrow’s Terminal Five.

At precisely 11.50am they wrenched off overcoats, tossed balloons, bouncy balls and some clothes into the air, and cried: “No third runway!”

The action was the first major protest since Geoff Hoon, the transport secretary, announced the go-ahead for a third runway and sixth terminal at Heathrow on Thursday.

Activists also said they were preparing to occupy homes in Sipson, the medieval village of about 700 homes which will be levelled to make way for the runway.

Under “adopt-a-residence” schemes, they would move into sparerooms of homes under threat and help owners with household tasks in order to be ready to stand in front of the bulldozers if they came.

Campaigners were also looking at schemes to buy patches of residents’ gardens in order to complicate compulsory purchase orders.

Greenpeace, along with about 10,000 celebrities, scientists, MPs and members of the public, has already bought a football pitch-sized plot of land earmarked for the new runway.

In an interview with the Guardian newspaper, the transport secretary dismissed the impact of the purchase.

“I suppose it adds to the numbers of people who have to be consulted,” Mr Hoon said. “But frankly I doubt that it would make a huge difference.”

He also criticised the hypocrisy of Emma Thompson, the London-based actress who co-owns the Greenpeace land yet flies to Los Angeles, prompting her to retort sharply.

“Get a grip, Geoff,” she told Mr Hoon. “This is not a campaign against flying - we're trying to stop the expansion of Heathrow in the face of climate change.”

Her comments followed after Mr Hoon told the Guardian: “I worry slightly about people who I assume travel by air quite a lot who don’t necessarily see the logic of their position.

“The reason we’ve got this problem in relation to Heathrow is that more and more people want to travel more and more.”

He did, however, concede that Thompson has been “in some very good films – Love Actually was very good”.