YouGov has been accused of suppressing polling which favoured the Labour Party following alleged pressure from Nadhim Zahawi.

       The polling company has denied pulling the 2017 election poll because it favoured Jeremy Corbyn, but said it was because its sample of voters was “skewed”.

       Chris Curtis, a former YouGov employee who is now head of political polling at Opinium, claimed on Twitter on Wednesday that it had been pulled because it was “too positive” about Labour.

       The poll allegedly showed that Mr Corbyn had won a debate in Cambridge “by a country mile”, even among one in four Conservative voters.

       “Despite having written the story and designed the charts, we were banned from releasing the story because it was too positive about Labour,” Mr Curtis said.

       He also alleged that the methodology behind the final poll released by the company before polling day had been tweaked and increased the Conservative lead, despite protests from staff.

       “This was done after pressure from high-ups (and despite protests from those of us who thought it wasn’t ok)”, he said.

       Mr Curtis also pointed to pressure which the polling company had received throughout the general election campaign over its modelling which showed Labour was closing the gap on Theresa May’s Conservatives.

       He referenced reported threats which YouGov had received from the now-Education Secretary Mr Zahawi, and Sir Lynton Crosby, the Australian political strategist who has advised the Tories on electoral strategy.

       A section from the book “Fall Out” by Tim Shipman recalled that Mr Zahawi phoned Stefan Shakespeare, YouGov’s chief executive, saying about its polling: “I’m going to spare you the agony: I’m going to call for your resignation when you’re wrong.”

       Mr Zahawi on Tuesday claimed that it was a “joke between two good friends”.

       “Stephan continues to be one of my closest friends and at no point since leaving YouGov in 2010 have I had any influence on the company. Suggesting otherwise is untrue,” he said.

       According to “Fall Out”, YouGov was also threatened by Sir Lynton.

       “I put Populus out of business last time. I’m going to put YouGov out of business this time,” he reportedly said.

       ‘We take our responsibilities seriously’

       YouGov later released a statement following the claims which denied the claims by Mr Curtis.

       “Chris Curtis’s allegation that we suppressed a poll because the results were ‘too positive about Labour’ is incorrect,” it said.

       “There was a poll run by Chris following the debate in Cambridge on 31st May 2017.

       “When reviewed by others in the YouGov political team, it was clear that the sample of people who watched the debate significantly overrepresented Labour voters from the previous election.

       “We take our responsibilities as a research organisation seriously and we could not have published a poll from a skewed sample that favoured any party. No serious polling organisation would have published this.

       “The idea that YouGov would suppress a poll that was ‘too positive about Labour’ is plainly wrong — as evidenced by the fact that in the 2017 election YouGov published an MRP model showing Labour doing significantly better compared to most other polling organisations.”

       Mr Curtis said in response: “I don’t remember this being the case, nor do I recall it being mentioned, but it may have been true that Labour voters were more likely to have watched the debate than Conservative voters and therefore taken part in the questions about the debate.”

       ‘Disinformation tactics’

       A Whitehall source told The Telegraph that they suspected Mr Curtis’ personal politics were motivating his attack on the Education Secretary.

       The now-pollster was a Labour party activist in 2015, having signed an open letter to the Parliamentary Labour Party about the lack of southern candidates running for leader.

       Mr Curtis did not comment on whether he was currently a Labour member .

       “I'm not sure I'd trust his analysis, given YouGov's scathing explanation of his sloppy poll, his links to Labour and his subsequent rowing back faster than a boat at the Henley regatta,” a Whitehall source said.

       “It looks like yet another example of the Labour left deploying disinformation tactics straight out of Putin's handbook.”