VOTE Leave, the group backed by Boris Johnson, Michael Gove and Chris Grayling, will be the official Brexit campaigners in the EU referendum.

They and the In Campaign were given the lead campaigner designation for the June vote by the Electoral Commission yesterday.

Members of the rival leave campaign, Grassroots Out, reacted angrily to the decision, with Arron Banks from Leave.EU saying he was considering a judicial review.

If that happens it could put the vote back until later on in the year. Banks said: “It is to be regretted that this process may put the referendum back until October but if we are to avoid the most important vote of our lives being rigged then I feel duty bound to take this course of action.”

But the founder of Grassroots Out, Tory MP Peter Bone, congratulated Vote Leave and said he wanted to get on with the campaign.

Professor Mona Siddiqui, chairwoman of the Scotland Stronger In Europe Advisory Group, welcomed the decision: “This is a very welcome step for the Remain campaign in Scotland and across the UK.

“Our campaign in Scotland is non-party political, positive in tone, and all about how the facts demonstrate that we are better off by staying in Europe.

“We are taking nothing for granted, but Scotland has the opportunity to come together in the EU referendum, uniting across other political divides to deliver a big Remain vote, and potentially have a decisive impact on the UK-wide result.”

A new poll for TNS said voters had not changed their mind in the last month, with remain on 35 per cent, leave on 35 per cent and the undecideds on 30.

However, when pollsters asked the undecideds how they might be leaning, 27 per cent were considering backing remain, a leap of ten points on the last poll. Leave were on 15, and 57 per cent of don’t knows insisted that they were still making up their minds.