VINCE Cable today tells Nicola Sturgeon that it would be a “big blunder” for the SNP not to support the Liberal Democrats’ push to hold a referendum to reverse the Brexit vote for fear it might harm the chances of having a second Scottish independence vote.

The Liberal Democrat leader claimed that another EU referendum was now more likely given the mounting problems surrounding Britain’s talks with Brussels on EU withdrawal and suggested Theresa May herself might be tempted to “take refuge” in holding another poll to “exit from Brexit”.

Last October, Ms Sturgeon made a rare comment on a second EU referendum, saying: "There may well be an argument for that."

When it was suggested Ms Sturgeon and her colleagues had not come out in support of EUref2 because they thought it would harm their push for a second independence vote, Sir Vince said: “That would be a big blunder; to put a minor tactical move ahead of the big picture.”

Sir Vince, in an interview with The Herald as the party faithful gather this weekend in Bournemouth for their annual conference, also said how they wanted to make Scotland a “Lib Dem bastion” once more as they promoted themselves as the “party of the two Unions”.

After the snap General Election, the Lib Dems were hoping for big gains on the back of their unique offer on Brexit: a second EU poll; “a referendum on the facts”.

But under Tim Farron’s leadership expectations were not fulfilled. Having slumped from 57 Westminster seats to just eight in 2015, this June the party gained only four more seats, three of which were north of the border. The Lib Dems remain Britain’s four party behind the SNP.

Mr Farron famously ruled out the prospect of his party going into coalition with either Labour or the Conservatives, declaring: “I want to be the Leader of the Opposition.” This seemed to confirm that none of the policies in the Lib Dem manifesto would ever be implemented.

Sir Vince made clear he was taking a different tack. “I’m standing as an alternative Prime Minister.”

When Lord Ashdown’s recent remarks were mentioned – that the party faced “existential challenges” and had not had “one big, dangerous idea” since the Coalition – the party leader bristled and said the Lib Dems had several radical policies.

“We have faced a big existential challenge for the last two years and contrary to the pessimists our membership has doubled to record levels and we see plenty of evidence of staging a comeback.

“We had quite a lot of edgy policies at the last election: a penny of the pound on the health service; the emphasis on mental health; the stuff on cannabis, which people may not have agreed with, was certainly pretty edgy. There was a lot of stuff, which was radical. I have talked to Paddy about it. I’m relaxed about him about being the elder statesman and a much revered figure,” he quipped.

Sir Vince then mentioned the Lib Dems’ flagship policy: its “referendum on the facts,” adding: “Paddy is wrong. We do have big ideas and we will develop them.”

As with life at Westminster, Brexit will dominate the conference season. The Lib Dem leader claimed, after talking to several civil servants, who used to work for him in the Coalition years, there was a great deal of alarm that the Prime Minister and her colleagues were “just making it up as they go along”.

He noted: “Whitehall has been increasingly panicky as they see the sheer magnitude of what’s involved. That’s why the administrative machine is desperate to have a transition to get this sorted out. But the problem is political as to whether the Tory Party could make that degree of concession.”

Sir Vince said he believed Brexit was now going so badly that the Lib Dems’ flagship policy of a second EU poll was gaining attraction across the parties.

Asked if EUref2 was now more likely, he replied: “It is. Certainly, on the Labour side some fairly plausible people like the Mayor of London and Andrew Adonis, who is very close to the Blairite wing, are arguing this is the way out and a lot of Tories are saying privately: ‘Look, if we do get into a terrible mess, this is one way of getting off the hook.’”

The Lib Dem leader even suggested Mrs May might begin to be tempted by the second poll idea given the difficulties her Government was experiencing as the clock ticked away.

“If the Government finds itself in a year or 18 month’s time with no agreement and a very damaging outcome, then it’s possible the whole process could grind to a halt. They may be tempted, as a growing number of people are, to take refuge in the policy we have been promoting; to give the public a vote.”

Asked if the SNP, who like the Lib Dems want the country to stay in the EU, should support the second EU referendum policy, Sir Vince replied: “I wouldn’t see why they would oppose it. Although they are clearly losing ground politically in Scotland at the moment.”

When it was suggested Ms Sturgeon and her colleagues had not come out in support of EUref2 because they thought it would harm their push for a second independence vote, Sir Vince said: “That would be a big blunder; to put a minor tactical move ahead of the big picture.”

The party leader said the “evidence suggests” the Nationalists had peaked in Scotland and that there were “big opportunies” for the Lib Dems here as politics became “polarised between a hard-line Tory UK Government and hard-line Labour and with the Nationalists losing ground because what are seen to be failures of the Scottish Government”.

He insisted: “We have a very distinctive offer, which is a positive one, as the party of the two unions.”

Now 74, Sir Vince brushed aside any suggestion he was too old to be the Lib Dems' leader, denying he had done a deal with his deputy, Jo Swinson, 37, for her to take over in a couple of years’ time.

“No, no, there’s no private deal. Jo would be just as offended as I am at the suggestion there has been[a deal] because her decisions have been made around her family.”

When it was pointed out to the Twickenham MP that by the time of the next scheduled election in 2022, he would be four days short of entering his 80th year, he replied: “Yes, well. I point out the gentleman on my walls, Gladstone, who went into office aged 82. This is the extreme scenario. As of now and for the foreseeable future, I’m very fit, up for it and perfectly happy to do it.”

Making clear how if he became PM in 2022, he would serve a full term ie until he was 84, Sir Vince added: “That would be the aim, of course. Politics moves very fast.”