Boris Johnson has pledged to cut income tax for people earning more than £50,000 if he is appointed as Theresa May’s successor, a proposal that has been labelled be “the biggest tax cut for the richest people in a generation”.

The Tory leadership hopeful has said he would use some of the cash set aside for no-deal Brexit planning to raise the 40p income tax threshold to £80,000 at, a cost of almost £10bn.

The higher rate of income tax currently applies on earnings over £50,000 in England and the move could benefit more than three million people.

But the proposals have been met with criticism, with Torsten Bell, director of the Resolution Foundation think tank pointing out that it would represent “a huge tax cut for higher earners”.

The median income in the UK is just over half of that, at £28,000, while in London it is just under £35,000.

In his regular Daily Telegraph column, Johnson said: “We should be cutting corporation tax and other business taxes.

“We should be raising thresholds of income tax – so that we help the huge numbers that have been captured in the higher rate by fiscal drag.

“We can go for much greater economic growth – and still be the cleanest, greenest society on earth.”

Under the plans someone earning £60,000 is estimated to see their tax bill fall by £1,000, the newspaper reported.

The move will cost an estimated £9.6bn a year and will be funded from the £26.6bn of “fiscal headroom” currently set aside by the Treasury for no-deal preparations.

It will also be partly offset by increased National Insurance contributions.

Johnson is estimated to be worth £1.6m, according to the Celebrity Net Worth website.

It comes as the race for the Tory leadership is hotting up, with rivals Jeremy Hunt and Michael Gove both launching their campaigns with Johnson fixed in their sights.

Health Secretary Matt Hancock and former Brexit secretary Dominic Raab are holding events to launch their campaigns, while Home Secretary Sajid Javid picked up further support for his campaign, with ministers Caroline Nokes and Victoria Atkins backing him.