John Healeyโ€™s plans to kick-start the economy have been thrown into doubt after Andy Burnham refused to back plans for a third runway at Heathrow. It puts him at odds with the Chancellor, who has given the ยฃ49 billion project his full backing.

The planned expansion would increase Heathrowโ€™s capacity to up to 756,000 flights a year and create up to 100,000 jobs. But Mr Burnham was unwilling to confirm he was in favour of the project going ahead. โ€œPrincipally, itโ€™s a matter for London and Londoners,โ€ he told the BBCโ€™s Sunday With Laura Kuenssberg, when asked if he would back the move. He diverted questions about his views, saying he would wait to hear the outcome of a consultation process on the matter.

โ€œItโ€™s not right for me to just jump straight in on the back of the consultation,โ€ he said. It comes as the 2035 deadline for the runway project has been pushed back by four years. Mr Healey will pledge a โ€œnew age of industrialisationโ€ for Britain in his speech to the Labour Party conference today (Tue) as he confirms the multi-billion pound projects will be built by British workers.

He will confirm that the Royal Navy’s submarine service at HM Naval Base Clyde will receive three new floating docks.

The government says the new facilities will provide crucial maintenance for the UKโ€™s current and future fleet of nuclear submarines.

The Chancellor has also committed to fund at least ยฃ115 million for a new marine research vessel to help protect our seas. Mr Healey said: “Britain has a proud shipbuilding heritage, and every pound of this strategic investment in a critical sector is backing British jobs on the Clyde and businesses across the UK, supporting growth in every postcode.

“By backing British shipyards, we are not only boosting national security but also securing resilience in the industries that will drive growth today while building the capabilities the country needs for the future.”

Mr Healey is due to deliver a crunch Budget in four weeks’ time with Britain in the grip of a cost of living crisis, high unemployment, sky-high borrowing and a spluttering economy. Both the Prime Minister and Chancellor have hinted at tough choices for the Government this autumn. The Labour leader said Mr Healey faces a โ€œchallengingโ€ set of circumstances at the Budget.

Mr Healey has signalled he is willing to make the case to Labour backbenchers over welfare reforms, as there was a โ€œmoral dutyโ€ to ensure a generation of young people get into work.

He has suggested that he could raise capital gains tax on October 28, something his Cabinet colleagues Louise Haigh and Wes Streeting called for over the summer.

Mr Healey has hinted he is mulling over whether a planned fuel duty rise should go ahead. โ€œIโ€™m conscious of these pressures and I will take them into account when I make my Budget decisions,โ€ he told the Times.