European Union states will not simply "roll over" and accept an independent Scotland a new member, the British government's chief legal adviser on Scottish law has warned.
The Advocate General for Scotland, Lord Wallace of Tankerness, said he expected existing EU countries, including Spain, to play "hardball" with Edinburgh in any accession negotiations.
Lord Wallace issued the warning during an interview with The Huffington Post UK, in which he also accused Alex Salmond of intimidating businesses, urged the pro-union campaign to be less "negative" and confirmed Scottish peers would be able to remain members of the House of Lords following independence - as long as they moved to the UK.
The minister, who is also the leader of the Liberal Democrats in the House of Lords, served as deputy first minister of Scotland from 1999 until 2005, having previously been the MP for Orkney and Shetland for 18 years.
Lord Wallace first questioned the SNP's assumptions about Scotland's EU membership in early October. And speaking to HuffPost UK he seized on comments by Spanish prime minister Mariano Rajoy as evidence Edinburgh would not have a "seamless" transition out of the UK and into the EU.
Rajoy, who is concerned about the precedent that could be set amid increased agitation in the Catalan region for independence from Madrid, suggested Scotland should not engage in "solo adventures".
Lord Wallace said: "I think it would be wrong for me as a UK government minister to speculate on whether Spain would veto membership. But he has indicated this isn’t a done deal. And I think it underlines the fact that this will be a political negotiation and some people will play hardball."
"At the end of the day it will require consent. It’s not just the rest of the UK that would have to agree to this, it’s the other states as well," he said.
Much of the debate over Scotland's potential membership of the EU has focused of varying legal interpretations on how the new country would join rather than the nature of its membership.
Lord Wallace cautioned: "The law will take you so far. The politics is the thing that actually matters. You’ve got to get 28 countries to agree. There’s lots of things to negotiate. I think the important point is that the 28 member states aren’t just going to roll over."
He said the SNP needed to admit there was "no guarantee" that it would be able to secure same out-outs that the UK currently enjoys, such as from the Schengen free movement agreement and the single currency.
He also said Salmond was wrong to argue that Scotland would gain a share of the UK's budget rebate. "The rebate is calculated by reference to the UK’s economy. If you take Scotland out of it the UK’s economy changes therefore the rebate will change. There will be no Scottish part. They’ve just got that wrong."
WHAT HAPPENS TO SCOTTISH LORDS?
If Scotland becomes independent following the referendum in 2014, the Westminster parliament would lose all its Scottish MPs. However Lord Wallace told The Huffington Post UK that Scottish peers who are members of the House of Lords would be able to retain their seats - as long as they moved their home south of the border following independence.
He said: "I happen to be a Scot who is a peer of the United Kingdom. So technically I would be able to retain my seat if [I was] a resident taxpayer."
"If I continue to keep my Orkney home, I would not be a resident taxpayer, so would not be able to keep my seat. My home is in Scotland. I have no intention of moving. I’m confident a year from now I will still be living in UK."
Lord Wallace, the deputy leader of the Lords and the most senior Lib Dem in the chamber, said that if Scottish peers decided to move to England, Wales or Northern Ireland it would "be fine" for them to carry on working in the British parliament as they would be UK residents.
Polls have consistently shown that Scots are yet to be convinced of the case for independence. Lord Wallace said he thought the anti-independence Better Together campaign headed by former Labour chancellor Alistair Darling was "winning the arguments". However he warned against complacency and indicated the pro-union campaign risked being seen as too "negative".
"We should talk up the positive more. It's not that we haven’t been doing it. But we have to talk up the positive. We have to turn the volume up," he said.
Lord Wallace said the UK was "something to celebrate" and that the Scots along with the English, Welsh and Northern Irish should be proud of how they had shaped a large part of the world together.
"This is in fact one of the most successful, if not the most successful, political, monetary and social unions in modern times. Not even modern. In history. Since the Norman conquest. If we didn’t have a UK today there would be a fairly compelling case for making one."
'SNP THREATS INTIMIDATING BUSINESSES'
In November the SNP unveiled its White Paper on Scottish independence. And Lord Wallace said the Westminster coalition government was surprised at how much of a damp squib it was.
"We spent weeks wargaming what sort of rabbits they might pull out of the hat, as one of my colleagues said: 'there wasn’t a rabbit, there wasn't even a hat'. There was nothing new. I was surprised. I thought they might have something," he said.
He added: "Alex Salmond is a very talented politician, he doesn’t walk on water as sometimes people think he does. Maybe he even does himself. He’s not invincible."
Earlier this week it was reported that several supermarket giants in Scotland were afraid to speak out on the business implications of independence - out of fear of censure from the SNP government.
Lord Wallace said the story was not a surprise. "I know businesses that won't put their head above the parapet," he said. And the peer, who plays a key role in the pro-union campaign, offered a "personal example" of the trend of companies being intimidated by the SNP. He confirmed reports that Loganair had withdrawn an invitation for him to deliver a keynote speech under pressure from Scottish civil servants.
"A company which invited me to speak at a company dinner told me I was personae non gratae. It was Loganair. I was asked if I would back down," Lord Wallace said.
He said he was on "pretty good terms" with the company and that incident was a "huge embarrassment" to the airline's recently retired chairman. "I don’t particularly want to rub it into him. I know it happens. I've had personal first hand experience."
Lord Wallace, who served as the MP for Orkney and Shetland from 1983 until 2001 before his career moved to Holyrood, was deeply involved in the creation of the Scottish parliament in the 1990s. And he admitted the architects of devolution did not think their plans would lead to an independence referendum as it was not thought possible for the Scottish nationalists to win an overall majority in Holyrood.
"I don’t think any of ever foresaw an SNP majority government," he said. "I think we foresaw a coalition government or one in which the SNP might be a part - over the whole span of decades.
"I think most of us who were involved in drawing up the blueprint, which the Labour government faithfully implemented, including the voting system, thought it couldn’t produce a majority government."
He added: "The SNP didn’t expect it either."