SCOTLAND is on the brink of independence, Angus Robertson, the SNP's leader at Westminster, has claimed, delivering the clearest signal yet that the party leadership is intent on holding a second referendum on the nation’s future.

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The hardening of the rhetoric by the 46-year-old Moray MP came as he set out his priorities in his campaign for the deputy leadership of the party and as SNP figures showed party membership had leapt by more than 4,000 since the Brexit vote to more than 120,000 – five times the number at the time of the 2014 No vote.

Earlier this week, Mr Robertson told Theresa May during Prime Minister’s Questions that “we in Scotland will do everything – everything - that is necessary for us to remain in the EU”.

Downing Street said that the PM would honour the UK vote that “Brexit means Brexit” and would fully involve the SNP Government in the exit process but it also made clear that Mrs May believed Edinburgh’s desire for Scotland to remain in the EU was “impracticable”.

Asked if Mr Robertson had misspoken or that the party leadership was indeed now intent on holding a second independence poll, a party spokesman said: "The SNP's priority is protecting Scotland's existing relationship with Europe given the clear decision of the Scottish people to remain in the EU.

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“As Nicola Sturgeon has made clear, this is an unprecedented situation not of our making and all options remain on the table – including a second independence referendum if it becomes clear that is the best or only option – and the First Minister has also made clear she believes an independence referendum is now ‘highly likely’.

“But,” he added, “the decision as to whether Scotland becomes an independent country will always be in the hands of the Scottish people."

Mr Robertson, who faces challenges for the deputy leadership from his colleagues Tommy Sheppard MP, Alyn Smith MEP and councillor Chris McEleny, said he would use his position as SNP deputy leader to "deliver our goal of independence".

The vacancy has arisen following the announcement by Stewart Hosie to step down from the position following controversy about his private life and a reported relationship with a journalist.

"We are on the brink of independence,” declared Mr Robertson, saying: “The campaign that comes now should be all about persuading people why our vision is the right one for Scotland.

"The SNP depute leader has a big role in order to make this happen; developing our policy, strategy and tactics to win.”

He stressed how he had spent the last year holding the UK Government to account every week at PMQs and that, alongside a team of extremely hard-working MPs, he had turned the SNP from the third party of the UK to the most effective opposition party.

Mr Robertson also said that he would seek to bring on board 5,000 pledged supporters to his campaign before the nominations closed.

"My vision for this role is about unity, campaigning and delivering our goal of independence," he added.

Meantime, new SNP figures showed that party membership had risen beyond 120,000 in the aftermath of the Brexit vote.

Membership now stands at 120,203, up by more than 4,000 since the June 23 result and a fivefold increase from the 25,642 members on the day Scotland voted No to independence in September 2014.

"The incredible upsurge in SNP membership shows no signs of stopping,” declared SNP business convener Derek Mackay.

He said the “extraordinary increase” in membership made clear it was the SNP which people trusted to stand up for Scotland's best interests; in contrast to a Labour Party in complete disarray north and south of the border and a Tory party which, he said, had taken Scotland to the brink of being dragged out of the EU.

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"That membership has grown substantially since the EU referendum vote is testament to the strength of feeling in Scotland that we must not be dragged out Europe against our will and the SNP in government will continue to explore every option to maintain our EU status," Mr Mackay added.