Campaigners held a colourful protest outside the House of Commons ahead of a Parliamentary vote on a third runway at Heathrow.

The demonstrators wore red t-shirts and held banners as they gathered in Old Palace Yard at 8am, to urge Labour MPs to support the opposition parties in a vote last night.

They held 57 red balloons to symbolise the number of Labour backbenchers who have signed Early Day Motions calling for the Government to think again about Heathrow expansion.

The debate was called by the Conservatives who used one of their debating days to try to embarrass the Government over its Heathrow policy.

John Stewart, chairman of campaign group Hacan, said: “This vote will not be binding on the Government but a close result one way or the other would be embarrassing.

"It would show once again just how little support there is for its plans for a third runway.

“The potential Labour MPs would win a lot of friends if they can summon up the courage to vote against the Government.”

Jamie Quinn, 28, of Brambles Close, Isleworth, said he hoped his MP Ann Keen would vote against the third runway.

He said: “In Isleworth we already feel the impact of living under the flight path, and the prospect of the number of flights increasing is quite a grim reality if the expansion goes ahead.

“In the Heathrow area we are already in excess of EU levels of emissions in particulates and I think it’s irresponsible to suggest that a third runway can be built and those emissions can be minimised.

“Local MPs and the Government need to try together to think about both the environmental and the health considerations of expansion.”

Actress Emma Thompson has written to the 30,000 people who have become beneficiary owners of a plot of land where the runway is due to be built, encouraging them to email the 57 potential Labour rebels asking them to “vote with their conscience”.