Workers in North Norfolk could be the hardest hit by the chancellor's controversial National Insurance Contribution revenue raiser.

Figures show the area has the highest proportion of self-employed workers in the region, who could see their tax bills rise after Philip Hammond unveiled plans for a 2pc hike in Class 4 national insurance contributions for the self-employed.

North Norfolk News: The highs and lows of being self-employed Illustration by Annette HudsonThe highs and lows of being self-employed Illustration by Annette Hudson (Image: Archant)

The move has been criticised by opposition MPs and a number of the government's own backbenchers.

Figures show that almost one in six people in the North Norfolk constituency class themselves as self-employed.

But the government has insisted that the move is fair in the light of the abolition of the separate Class 2 payments as well as improvements to the benefits received by self-employed people.

A review of modern employment practices by RSA chief executive Matthew Taylor, due to report over the summer, will be followed by a Government paper which is expected to include proposals to extend benefits such as parental leave to the self-employed.

But North Norfolk MP Norman Lamb said: 'These changes will come as a major shock the thousands of self-employed people in Norfolk already facing a hit to living standards from rising prices.

'The Conservatives have broken a clear manifesto pledge.'

In a Brussels press conference on Thursday, the prime minister promised to listen to concerns raised by Conservative MPs and said there would be no vote until the autumn on the £2 billion hike in NICs for the self-employed.

She acknowledged that the Budget had meant 'difficult decisions' but insisted it was vital to close the gap between the amount of tax paid by the self-employed and those in 'traditional' employment.

The rise in people in self-employment risked eroding the tax base, leaving public services short of funding, she warned.

And she said: 'This is a change that leaves lower-paid self-employed workers better off; it's accompanied by more rights and protections for self-employed workers and it reforms the system of National Insurance to make it simpler, to make if fairer and to make it more progressive.' Labour has opposed the move.