Boris Johnson risks pushing Scotland further towards independence unless he faces the crisis in the union, Sir John Major has warned.
The former prime minister said choosing not to grant Scotland another referendum on its future without drastic changes to the devolution settlement would give a massive boost to the SNP.
Writing in the Financial Times, he wrote: “Scotland cannot be kept forever in an arrangement if her people wish to end it. Boris Johnson probably has a legal right to refuse to sanction a second independence referendum. But he should be wary how he uses that power.
“It is unwise to dismiss Scottish ambitions, or to delay any vote, without action to expose the reality of separation – and remedy shortcomings in the UK’s devolution settlement.
“A blunt refusal would be a still greater error if accompanied by the provocative assertion that Scots should wait another generation before voting again. Such a hardline approach is more likely to provoke a break-up than prevent it.”
The former Tory leader added that the UK government should order an “independent assessment of the pros and cons of separation”.
“If the two governments will not commission such studies, then their parliaments should – and academia, too,” Sir John said.
“In parallel, the UK must address any constitutional amendments thought to be necessary by changed circumstances, frictions in the devolution settlements or the impact of Brexit.”
He went on to say that while Scotland was as a “proud nation perfectly capable of self-government”, there is still a chance to persuade the country’s residents to remain in the union “with facts and reason”.
He said: “The economic cost of separation would be harsh on Scotland. There is no longer an oil bonanza to boost the economy. The fiscal deficit is above 7 per cent of economic output.
“Over 60 per cent of Scottish trade goes to the rest of the UK, three times her trade with the EU. Does Scotland really want a trade border with England?
“The ‘Barnett Formula’ boosts Scottish public spending by nearly £2,000 per person per year from Westminster. If lost, can Scottish taxpayers make up that sum? This is not Project Fear. It is reality.”
Boris Johnson has previously branded the SNP’s push for a second referendum “completely irrelevant” and ruled out holding a vote on the issue while he is in office.
The Prime Minister has also suggested the 41-year period wait between the UK’s two referendums on Europe – the first in 1975 and the second in 2016 – was the “right sort of gap” for a second vote.
Meanwhile, Alex Salmond has announced his return to politics to lead a new pro-Scottish independence party called the Alba Party.
Scotland’s former first minister named himself head of the new party at a press conference on Friday afternoon, in the midst of a high-profile inquiry into the handling of harassment allegations made against him.
The party plans to stand at the Scottish Parliament election on 6 May in regional list seats.