A senior SNP MP is urging party leaders to make the preparations for holding a second vote on independence without waiting for Westminster to consent to such a ballot.

While First Minister Nicola Sturgeon has shied away from holding a consultative referendum, Joanna Cherry QC insisted that “now is the moment to begin the preparations”.

She said on Twitter: “Boris Johnson should be put on notice that we have options & we are not afraid to push forward.”

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The SNP home affairs spokeswoman at Westminster suggested Holyrood should pass a Bill to hold a consultative referendum, and then let the PM mount a legal challenge on whether they had the power to do so.

Such a case would be decided at the UK Supreme Court, with Ms Cherry stating: “Many legal experts think we would win the argument.”

Setting out her case on Twitter she said “now is the moment to begin the preparations. To tell Johnson “see you in court” if he continues to block Scotland’s demand for #Indyref2″.

She spoke out as a poll showed a majority of Scots were in favour of Holyrood legislating to hold a referendum, if Westminster continues to block demands for a vote on the continuation of the Union.

The Panelbase survey asked people for their views on what should happen if the UK Government continues to refuse to give permission for an independence vote – asking if the Scottish Parliament should legislate for such a ballot and then allow the courts to decide if it could go ahead.

Of those who expressed an opinion, 56% agreed with such an approach, with 44% opposed.

Ms Cherry, who was involved in the successful legal challenge to the PM which last year saw the prorogation of Parliament ruled as unlawful, argued that taking this stance could “move us away from the current impasse” – which has seen both Theresa May and Boris Johnson refuse requests from the First Minister for Holyrood to be given the powers to hold a referendum.

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She stated: “I believe that Holyrood passing a Bill to hold a referendum could be part of a multi-faceted strategy to move us away from the current impasse & stop the constant and unproductive talk about Section 30 orders & seeking “permission” to act from Westminster.

“The balance of legal opinion is that we might well win any court challenge & I don’t believe that losing would set us back any further than where we are just now.”

Nicola Sturgeon delivered a statement on the ‘next steps towards independence’ on the day the UK formally left the EU (Jane Barlow/PA)

Ms Sturgeon insisted she would not sanction a “wildcat” unauthorised referendum, as was held in Catalonia, when she set out her “next steps” towards independence at the end of January.

However, she said then that there could come a time when the Scottish Government would consider holding a consultative vote – if this was ruled to be legal by the courts.