Hounslow MPs Ann and Alan Keen have been accused of failing to make any impact in the Heathrow airport expansion debate.

Conservative parliamentary candidate Mary Macleod said it was “disappointing” that after holding their seats for 11 years, the couple had been unable to influence the Government over proposals for a third runway.

She said: “This is the most important issue locally and you have to come out clearly and firmly and do all you can to make sure you try to persuade your fellow politicians to your way of thinking. It is action that’s needed now and not just words.

“The only way you can make change happen is if you can really try and persuade people to your point of view, that’s what I think they haven’t done enough of.”

The candidate for Chiswick, Brentford, Isleworth, Osterley and Hounslow said the Keens should have been “extremely vocal” in campaigning against the biggest issue affecting their constituencies.

She added: “Ann Keen is a Government minister so she has got influence, it would have been great if she could have taken up the mantle and pushed the Government on it, because that way she really could have made a difference to the debate, but she didn’t.”

Mrs Keen’s office hit back saying Ms Macleod’s comments were “ill-informed,” adding that both Alan Keen, MP for Feltham and Heston, and his wife, MP for Brentford and Isleworth, had opposed Heathrow expansion for “many years”.

A spokesman for Health Minister Mrs Keen said: "Having lived in the constituency for 21 years, both Ann and Alan have campaigned on the issue since 2002 when Ms Macleod was still deciding where to focus her parliamentary ambitions.

“It is interesting to note that David Cameron's Conservative party have only recently jumped on the bandwagon in opposing the third runway, at a time when the really difficult decisions are being made.”

He added: "Ann and Alan have always understood that this is a more complicated issue than that, and involves noise and pollution on the one hand, and jobs and the economy on the other. In the present climate, that makes reaching an informed decision - as opposed to jumping on the nearest bandwagon - a matter of the utmost seriousness."

When asked whether the Keens believed Heathrow expansion should be put to a vote in the House of Commons, he said: “Their current position is let's wait and see what the final decision is.”

A poll commisioned by Greenpeace claimed constituencies under the Heathrow flightpath would swing almost 5 per cent from Labour to the Tories because of the prospect of a third runway, leading to Mrs Keen losing her seat at the next general election.