The first-ever ConservativeHome poll of Party members on the Europe, remaining and leaving, and the Prime Minister’s renegotiation sees two-thirds of them ready to vote for Brexit.

According to the survey, conducted last week, 66 per cent declare themselves likely to support quitting the EU, and 30 per cent likely to back staying in it.

When ConHome last polled Party members on the matter in June, the percentage in favour of remaining was exactly the same, while 58 per cent were in favour of leaving.

That particular survey question, however, simply gave respondents a binary choice between staying and quitting.  This latest version attempts to take David Cameron’s planned renegotiation into account.

We asked: “On the basis of what you know about the Government’s EU renegotiation plan, and your assessment of likely reactions to it here and abroad, are you more likely to vote to remain in or to leave the EU in the coming referendum?”

The result of the poll suggests that the Prime Minister’s renegotiation plans make little difference, at least yet, to their assessment of how they are likely to vote when the referendum comes.

Indeed, the proportion believing that they will support Brexit is larger than it was during the summer when they were presented with a simple choice between staying and quitting.

I would be surprised if Cameron is unable to persuade a larger percentage of Party members than roughly a third to support remaining in the EU.

It’s reasonable to assume that such will be his position when the referendum comes, and I would expect that his view will move some members from the quit to the stay side of the ledger.

However, this result indicates that there is strong support within the Party for leaving the EU, and that there is a solid floor beneath which backing for it is unlikely to drop.

The Prime Minister was wise to accept the Electoral Commission’s recommended referendum question, and the Party sensible to declare that it will remain neutral throughout the campaign.

The next best step for unity is for Mr Cameron to declare that, come that campaign, Government Ministers and front-benchers will have the freedom to speak and vote as they wish.”

On Tuesday, Steve Baker, the Co-Chairman of Conservatives to Britain, will be discussing the case for Brexit at a ConHome fringe meeting.

It will take place in the ConHome Conference marquee, inside the secure zone, at 2.30 in the afternoon.

Almost a thousand party members responded to the survey, which drew over 2000 replies in all from ConservativeHome readers.

When the view of all readers was measured in the poll, backing for quitting the EU rose to 72 per cent, and for staying fell to 24 per cent.