High earners will not face any increase in income tax under a new Conservative government, one of Theresa May’s most senior ministers has promised.

Sir Michael Fallon, the Defence Secretary, said voting Tory was “the only way” workers across the wage spectrum could be sure their tax would not go up, ending weeks of uncertainty for middle-class professionals.

The pledge puts clear water between the Tories and Labour on personal tax, with Jeremy Corbyn promising to increase income tax on those earning more than £80,000 to help pay for a £50 billion giveaway.

It comes amid concern among senior Tories about the party’s vanishing lead in the opinion polls, which was once as high as 24 percentage points over Labour but is now as low as three per cent.