Prime Minister Theresa May has remained silent on whether the Conservatives will renew its "tax lock" on income tax, VAT and national insurance. The lock was installed by David Cameron and George Osborne before the 2015 general election, but comments by chancellor Philip Hammond suggested it could come to and end to allow tax increases.

Speaking in Washington DC, Hammond said while he did not believe in high taxes, it was "self-evidently clear that the commitments that were made in the 2015 manifesto did and do today constrain the ability to manage the economy flexibly".

Labour said the chancellor's words signalled a "Tory tax bombshell" but when asked about the tax lock on Saturday (22 April), May was tight-lipped.

"Let's be very clear on the issue of taxation," she told supporters in Dudley. "At this election, people are going to have a very clear choice. They will have the choice of a Conservative Party, which always has been is and will continue to be a party that believes in lower taxes in keeping taxes down for ordinary working people and we've shown that.

"For example, we've taken four million people out of income tax altogether, 31 million people have seen a tax cut under the Conservatives. Or the choice is a Labour Party whose natural instinct is to always raise taxes and if you need any evidence of that just look at that their former shadow chancellor said about Labour Party policy.

"He said it would lead to a doubling of income tax, a doubling of national insurance, a doubling of VAT and a doubling of council tax. That's the choice: lower taxes under the Conservatives or higher taxes under Labour."

Campaigning in Manchester, Jeremy Corbyn would not commit to the tax lock, but said that under Labour the tax burden would not fall on the shoulders of those with low incomes. He also vowed to protect the triple lock on pensions.