THE SNP has been placed on a war footing for a second tilt at Scottish independence after its Westminster leader made clear the party's preference was for another vote on the Union rather than a second EU referendum.

At the weekend after around 100,000 people marched in London to demand the public be given the final say on the Brexit deal, Ian Blackford said he was keeping an “open ear” to the argument for holding a second referendum on the UK’s membership of the EU; the so-called “people’s vote”.

But yesterday the Highland MP sought to clarify the position of the SNP leadership; that its clear preference was for a second vote on Scotland’s future not on EU membership.

He explained if there were a proposition for a second EU vote, then the SNP “wouldn’t stand in the way of that”.

But Mr Blackford stressed: “We already have a mandate from the people of Scotland and the Scottish Parliament if there’s a material change of circumstances, then we should have a discussion with the people of Scotland on a vote on independence and if we were talking about a ranking choice as to what our preference would be it would very much be for a decision of the Scottish people on their constitutional future rather than anything else.”

He pointed out how a second EU vote could potentially complicate matters with a view to holding another independence referendum.

“For example, if we end up in a situation if the rest of the UK voted No again and Scotland voted to remain, how is our position protected? So there are some real issues with that second EU vote.”

Mr Blackford denied “threatening” a second independence vote but stressed that having the option of staging one was “the reality of the situation; it’s an awful lot easier because we already have a mandate for that”.

When it was pointed out that Theresa May had repeatedly made clear “now is not the time” for a second independence poll and the UK Government would not facilitate one before the 2022 General Election, the Nationalist leader said: “I would respectfully say to Theresa May: she has to respect the will of the Scottish people and the Scottish Parliament; if that is what we end up doing.”

But when pressed that the Prime Minister, facing all the pressures of Brexit, would simply not sanction the extra constitutional turbulence of a rerun of the 2014 poll, Mr Blackford added: “Let’s wait and see.”

Last week, Peter Grant, the SNP’s Europe spokesman, suggested a hard Brexit would lead directly to Scottish independence. He told MPs there was "not a rope in existence that is strong enough" to hold Scotland to the rest of the UK if the Conservative Government pursued a hard, cliff-edge Brexit.

Mr Blackford’s pointer to what is likely to happen later this year follows a number of recent developments that suggest the leadership is preparing its troops for a new constitutional battle ahead.

This week, the SNP’s deputy leader Keith Brown quit as the Scottish Government’s Economy Secretary to devote himself to building the case for independence and preparing the party for future campaigns.

Earlier this month at the party’s Aberdeen conference Nicola Sturgeon said the party gathering had marked the “start of a new chapter on Scotland's road to independence” while the First Minister insisted the publication of the party’s Growth Commission report on the economics of independence showed "small, independent nations can be successful and often more successful than larger nations".

At Westminster, the SNP has begun a campaign to “frustrate” the UK Government’s business following its decision to press on with the flagship EU Withdrawal Bill despite opposition from Holyrood.

In protest, Mr Blackford, a fortnight ago, led a mass walk-out of his party’s from the Commons chamber and has promised a campaign of disruption over the coming weeks and months.