David Cameron's hopes of remaining in Number 10 on his on terms have been boosted after a Brexit-backing group of MPs has told him it is his duty to stay.

North-West Norfolk MP Sir Henry Bellingham has orchestrated a letter, which has says has been signed by the majority of leave MPs, which says: 'We who are supporters of Vote Leave and are members of the Conservative parliamentary party, thank you for giving the British people a choice of their destiny on June 23 2016. We believe whatever the British people decide you have both a mandate and a duty to continue leading the nation, implementing our 2015 manifesto.'

The letter was released at 10pm as the polls closed after a busy day of voting. Returning officers reported a busy day with many people opting to vote early.

Those heading to polling stations during the evening rush braved torrential rain and thunder storms.

South Norfolk MP Richard Bacon also signed the letter organised by Sir Henry. North-East Cambridgeshire Stephen Barclay has not signed the letter because he is a government whip, but said the prime minister had his support regardless of the result.

Conservative veteran Sir Henry said he 'deeply deeply regretted the way the national campaign has been run'.

'It is a great pity it has become so heated and so personal and so antagonistic. I think it is a great great shame.'

He said that while he thought the prime minister should have replicated Labour prime minister Harold Wilson's approach in the last referendum in 1975 by not leading one side of the campaign, it was essential Mr Cameron stayed on, whatever the result.

In Essex Vote Leave supporters, including Colchester MP Will Quince and Braintree MP James Cleverly, have singed a letter telling the prime minister he has a 'mandate and a duty to continue leading the nation'.

Harwich MP Bernard Jenkin said he had not signed the letter, but had communicated directly with Mr Cameron expressing hope that he would stay on. Witham MP Priti Patel could not be contacted.