JOANNA Cherry will tomorrow call on Nicola Sturgeon to consider pressing ahead with plans to hold a legally binding independence referendum if Boris Johnson continues to reject the Scottish Government's request to transfer powers for a new plebiscite to Holyrood.

Writing in The National, the SNP MP points to the First Minister's Brexit day speech in January where she suggested a second referendum may be within the remit of Holyrood and that such assessment has been made by a range of constitutional experts.

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"I have never advocated a wildcat or illegal referendum," writes Cherry. "My interest is in the question of how Scotland might hold a legally sanctioned referendum on the question of independence without having to be dependent on the Westminster Government’s permission.

"Earlier this year, in her speech marking Brexit day, the First Minister acknowledged that it might be within the competence of the Scottish Parliament to hold an independence referendum and she spoke of the possibility of testing that in court, albeit she indicated she was reluctant to do so at that stage."

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She adds: "The argument that the Scotland Act could be read in such a way as to allow Holyrood to hold a referendum on the question of independence is well established. In 2012, before the Edinburgh Agreement was reached, seven legal academics including three distinguished professors published a paper challenging the view that only Westminster has the authority to call an independence referendum.

The National: First Minister Nicola Sturgeon during her Brexit Day speechFirst Minister Nicola Sturgeon during her Brexit Day speech

"Recently, one of the authors of that paper, Professor Aileen McHarg and her senior colleague Chris McCorkindale, reaffirmed this view, pointing out: “Although it is frequently asserted that a referendum on independence falls outwith devolved competence (as part of the reservation to Westminster of ‘the Union of the Kingdoms of Scotland and England’, Scotland Act 1998, Schedule 5, Part 1, para 1(b)), that issue has never been conclusively settled.”

Cherry, a QC and the SNP's home affairs and justice spokeswoman at Westminster, warns internal critics "the words #nodebate should have no place in the SNP lexicon" as she stresses the need for discussion on the route ahead.

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She points out that while she does not support the Plan B advanced by fellow SNP MP Angus MacNeil and Inverclyde Councillor Chris McEleny – which involve using the 2021 election as a proxy vote on independence – she does back a need to come up with a way forward to respond to the Prime Minister’s block.

"For the record, I have not endorsed the Plan B advanced by Angus Brendan MacNeil and Chris McEleny," she writes.

"I am not sure that plan has been fully developed or addresses how you bring the UK Government to the negotiating table, which will be vital. However, I think the SNP should consider what we do if Boris Johnson continues to refuse a Section 30 Order and I applaud Angus and Chris for trying to stimulate that debate."