Ahead of the manifesto launch later this week, McDonnell said Labour would promise not to increase income tax for those earning below £80,000 and would not increase the rate or change the scope of VAT or National Insurance.

However, McDonnell made clear that ‘higher earners’ would be asked to make a ‘slightly bigger’ contribution. While he said this would apply to those earning more than £80,000, the shadow chancellor did not provide details of how this would be done. The two main options are to bring down the current threshold for the 45p rate of income tax from £150,000 to £80,000, or to introduce a new intermediate rate.

McDonnell said: ‘The choice at this election is very clear on tax, as there is currently only one party which is committing not to raise taxes on middle and low earners – and that is the Labour party.

‘If Labour is elected next month we will guarantee that for the next five years there will be no tax rises for income taxpayers earning less than £80,000 a year, no hikes in VAT and no changes in your national insurance contributions either.

‘The Labour party is now the party of low taxes for middle and low earners, while the Tories are the party of tax handouts for the super-rich and big corporations.’