A Tory MP has warned that the Prime Minister will have failed as a leader if he refuses to back a third runway at Heathrow airport.

Supporters of the expansion plan say that a third Heathrow runway (LHR3) is required to prevent France, the Netherlands and other European rivals snatching aviation business from the UK – and to help grow the UK economy.

“The Prime Minister must ask himself whether he is man or mouse,” Yeo told the Daily Telegraph. “His place in history is assured as the leader who made the Tories (nearly) electable again, an achievement that eluded three previous leaders. But does he want to be another Harold Macmillan, presiding over a dignified slide towards insignificance?”

Yeo added that the development of the third runway would provide a much-needed economic stimulus without costing the taxpayer a penny.

Since 2008, Conservative Party policy has been to oppose LHR3. And BBC political editor Nick Robinson points out on his blog that Cameron is desperate to avoid a toxic situation the like of which swamped Nick Clegg over the Lib-Dem U-turn on tuition fees.

Even Yeo himself once opposed LHR3 on environmental grounds – but now says he has changed his mind due to a weaker-than-expected European economy, and the advent of environmental regulations that should lead to the development of cleaner aircraft.

Transport secretary Justine Greening this morning rejected Yeo’s call. But with business leaders, many MPs from both sides of the house, and even some government ministers reportedly backing a change of heart, the row is likely to continue.