Londoners divided on third runway as activists hurl bricks

The YouGov survey found 43 per cent opposed the £9billion scheme, compared with 35 per cent in favour, and 22 per cent who did not know.

The results, which reveal clear gender, age and geographical divides, came as a series of protests began by activists determined to halt the expansion plans.

Climate change activists launched a pre-dawn raid on the Department for Transport today.

Hundreds of demonstrators will protest at Terminal Five tomorrow and there are plans to bring Heathrow to a standstill for 24 hours.

This morning three women wearing red sashes hurled bricks wrapped in paper which read "No third runway, the suffra-jets are back" at glass doors in the department on Horseferry Road, Westminster.

Police were called just after 5am and were investigating claims that paving slabs were used to break the window.

A spokeswoman for the protesters said they hurled green paint to symbolise the "green wash" they heard from the Government yesterday as Transport Secretary Geoff Hoon announced he would allow the third runway.

The plan will increase the number of flights from 480,000 to 702,000 by 2030. Mr Hoon bought off some backbenchers with safeguards such as the rejection of "mixed-mode" operations that would have meant all-day take-offs and landings.

The Standard's survey showed that opinion in west London is more polarised than the capital as a whole, with 50 per cent opposed and 37 per cent in favour of the expansion. Just 39 per cent of men oppose a new runway while 45 per cent are in favour. Among women, 46 per cent are opposed and 26 per cent in favour.

The starkest division comes over economic and green impacts of the runway. Some 58 per cent agree it would bring benefits in terms of jobs, with 17 per cent disagreeing. Some 38 per cent of all Londoners feel the dangers of climate change are so severe there should be no airport expansion at all.

Tomorrow's flashmob protest at Terminal Five, planned months ago by campaigners Plane Stupid, will be the first large-scale protest since the decision was announced.

Leila Deen, Plane Stupid spokeswoman, said: "We expect this to be big. Despite all the objections, arguments and all the science, the government is determined to support the aviation industry over the future of life on earth. We say - bring it on."

At noon protesters will enter the T5 departure lounge and pelt images of Geoff Hoon with red sponges. Numbers are expected to be swelled by local residents angry at the decision to go ahead with the runway.

The protest is designed to be peaceful, but police are aware of rising anger among those who feel their attempts to stop the runway have been unfairly ignored. One resident said: "The key thing is not to allow protests to get so angry that they alienate people who are now supporting them."

Tory supporters are split down the middle on the decision, with 39 per cent both in favour and against. Labour supporters are similarly divided, but Liberal Democrats are much more opposed. Some 56 per cent of Lib Dem voters are against the runway, compared to 30 per cent in support.

Despite the youthful image of green activists, the most staunch opposition comes from older voters. Among the over-55s, 53 per cent are opposed compared with 33 per cent backing. Among 18 to 34-year-olds, there is a three-point gap between those on either side of the argument.