Plans for a third runway at Heathrow Airport face renewed political uncertainty if Andy Burnham becomes Prime Minister. Theresa Villiers, former Transport Secretary, warns that Burnham is not an enthusiast for the project, putting its future in jeopardy, especially given its estimated cost of around $63.7 billion. This comes despite the Labour government's official support for Heathrow's expansion and ongoing public consultation on an updated Airports National Policy Statement.

Burnham, widely anticipated to succeed Keir Starmer as Prime Minister, has previously argued that Heathrow expansion diverts investment and economic activity away from northern England. Net Zero Secretary Ed Miliband has also voiced opposition unless the expansion aligns with the UK's legally binding climate commitments. London Labour MPs who oppose the project are reportedly hopeful that Burnham will cancel it, citing his past comments and the belief that the project is financially unviable and environmentally damaging.

However, supporters of the project, including Heathrow itself, argue it would create jobs, boost economic growth, and improve connectivity. They stress that the project is privately funded and backed by businesses, trade unions, and industry groups. Willie Walsh, Director General of the International Air Transport Association (IATA), acknowledges the economic case but raises concerns about the project's rising costs, which he believes could make it difficult for airlines to support due to potential increases in airport charges. London Mayor Sadiq Khan remains resolutely opposed, citing concerns about air quality and climate targets.

There is a possibility of a compromise, with one source suggesting Burnham might consider an alternative proposal by hotel tycoon Surinder Arora. This plan would involve a shorter third runway on the airport's existing footprint, avoiding the need to tunnel part of the M25 motorway. While the project has government backing from figures like Rachel Reeves and support from the Labour Growth Group for its economic benefits, the combined opposition from Burnham, Miliband, and Khan, alongside environmental concerns and financial viability questions, leaves the third runway's future highly uncertain.