ANTI-HEATHROW expansion activists slammed Rachel Reeves for “mis-selling” the third runway to the Treasury as she prepares to leave No 11 when Andy Burnham becomes PM in just over a week.

The likely outgoing chancellor convinced her department to back the project with “panglossian figures” without commissioning an impartial economic assessment, campaigners said.

No 3rd Runway Coalition chair Paul McGuinness accused Ms Reeves of using data commissioned by Heathrow Airport to “coax” her Labour colleagues into supporting the expansion.

Mr McGuinness said: “It seems astonishing that, rather doing the due diligence of instructing the Treasury — her own department — to conduct an impartial assessment of the economic case for Heathrow expansion, Rachel Reeves chose to pluck panglossian figures from a report that had been commissioned and financed by Heathrow airport to coax her government colleagues and Parliamentary Labour Party into backing Heathrow expansion.

“And that even after her department’s own objective calculations had shown that Heathrow expansion could offer no economic benefit to the UK, she continued to cite figures that are derived entirely from Heathrow’s own sales puff.

“It is all but clear that Rachel Reeves recklessly mis-sold Heathrow expansion to her Cabinet and the governing party.”

Mr Burnham has indicated he would replace Ms Reeves if he is appointed PM on July 20, but has yet to confirm who he would choose for the job.

Campaigners took particular issue with Ms Reeves’ claims that adding a third runway to Europe’s busiest airport would deliver up to £42 billion in economic benefits and increase national GDP by up to 0.43 per cent by 2050.

They claimed that these figures come from a report by Frontier Economics, produced for Heathrow Airport.