HOLYROOD could lawfully legislate for a second independence referendum if it was made clear that the ballot was consultative and not legally binding, a former top Tory MSP has said.

Professor Adam Tomkins, the John Millar Chair of Public Law at the University of Glasgow, made the assertion in a column for The Herald on Wednesday.

It comes as the Scottish Government announced that Nicola Sturgeon would give a ministerial statement on plans to hold a second independence ballot with or without a Section 30 order from Westminster.

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Ahead of the 2014 referendum, the London government granted a Section 30 order, which allowed Holyrood to legislate in reserved areas and avoid the legal questions surrounding the issue.

Whether the Scottish Government has the power to legislate for a second independence referendum is up for debate.

The Scotland Act reserves the Union to Westminster, but Holyrood is considered to have the power to hold referendums. The crux is whether it can hold a vote that “relates to” a matter which is reserved.

Reports say that Sturgeon’s government plans to hold a consultative ballot, which would not be legally binding and so would not impinge on the reserved area of the Union directly.

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However, a blog post on University College London’s “Constitution Unit” written by journalist turned constitutional researcher David Torrance suggested that the Supreme Court would have little time for such arguments and that a Holyrood bill would be deemed unlawful.

It stated: “The ‘purpose’ of an ‘advisory’ or ‘consultative’ referendum would remain that of achieving independence, and it would therefore ‘relate to’ a reserved matter.”

However, Tomkins (below) has argued differently in his column for the Herald.

The National:

The former Tory MSP said the Scottish Government could “hollow out the referendum … insisting that its purpose is not to end the Union (a reserved matter) but simply to consult the Scottish people and that its effect is, in legal terms, nil”.

“Such a go-it-alone referendum would be lawful,” he adds.

However, Tomkins is sceptical of the value of such a vote, going on: “It would also be pointless, not least because those opposed to doing this whole damn thing again will stay at home, ignore it, and boycott the vote.”

Scottish Tory leader Douglas Ross has said he would boycott an "illegal" vote, but it is unclear if he would hold to that stance if such a consultative ballot were deemed legal.

The professor says that the Brexit vote led to a mess because there was no unity of purpose among those who voted Leave, so no-one was quite sure what the Brexit the public had voted for actually was.

He says that Scottish independence faces a similar issue, with questions such as currency, the Border, and Trident currently unanswered.

Tomkins wrote: “Let’s figure out what independence would actually look like in practice – what it would actually entail – first and, only then, only after we have done that, ask the people whether they think Scottish independence really is what they want.”

These issues are among those which the Scottish Government has said it will address in a series of white papers making the case for independence, the first of which was launched by Sturgeon and Greens co-leader Patrick Harvie earlier this month.