THE Yes movement would be “snatching defeat from the jaws of victory” by setting up a new pro-independence party to challenge the SNP next May, according to a former top Tory spin doctor.

Andy Maciver, ex-director of communications for the Scottish Conservatives, said that Boris Johnson could use any list seats won by the Alliance for Independence to put up a new barrier to indyref2.

Writing in the Herald, Maciver said “a perceived manipulation of the voting system” could give the UK Government a new reason not to grant the Section 30 order request. Most pressure on Johnson to grant the request would come from a single party's clear manifesto commitment to a second independence referendum rather than from “a muddying of the waters as a result of blending different manifesto commitments'', he added.

"On the face of it, AFI is a clever concept, exploiting the SNP’s strength in constituencies, peeling off the wasted SNP regional votes, and scooping up a large proportion of the 56 regional seats," wrote Maciver, who is director of public relations firm Message Matters.

"The legitimacy or otherwise of ‘playing’ the Additional Member System (AMS) voting method is for another column, but as an exercise in maximising the number of seats for pro-independence parties the AFI proposal has solid logic.

"However, this is not solely about electoral success in May. The entire purpose of the exercise is, I presume, to lay the foundation for a second independence referendum. However, without the consent of Westminster, nationalist parties could win 100 seats and there will still not be a second referendum."

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He added: "There remains a debate in the Conservative Party about the granting of indyref2. The official line remains that there will not be one. We’ve had one, we said no, we meant it, you said ‘once in a lifetime’ and so on and so on. Many influential figures at Westminster want this to remain the position; others, though, understand the long term difficulties in repeating that age-old unionist mistake of ignoring what Scottish people have expressed a clear wish for, and hoping it will all be forgotten about.

"So what are the conditions under which the UK Government will find it most difficult to deny another referendum? The answer to that is, in my view, a single party, SNP-only majority. This entails a single, clear manifesto commitment, and a single party being elected on that platform.

"A perceived manipulation of the voting system will give the UK Government an ‘out’; a muddying of waters as a result of blending different manifesto commitments will give the UK Government an ‘out’; the inclusion in the majority of a party linked to a more colourful and outlandish branch of nationalism will give the UK Government an ‘out’."