Darling headed up the pro-union Better Together campaign during the 2014 Scottish independence campaign and hit out after the SNP confirmed it will seek to change policy at its forthcoming party conference to pursue a separate Scottish currency after independence. This would follow a transitional period after a Yes vote which would see the pound retained.
But Darling told the Sunday Times: “A new currency would be the new kid on the block, so you have to persuade Scots who have their mortgages, investments, pensions and other savings in sterling that their money will be safe in an untried currency.
“Meanwhile the harsh fact remains that most of Scotland’s trade is with England. You will have a transactional cost for trading with England with a different currency so you are simply adding to the expense of doing business and that’s not good for your economy either.”
He added that the SNP’s commitment to rejoining the EU would also mean signing up to the euro.
“Just look at the costs involved in transferring from sterling to a Scottish currency and then from a Scottish currency to the euro in, say, five years. It’s simply not practical.”
The SNP insists that joining the EU, despite the commitment to the euro, would not necessarily mean adopting the currency. It points to Sweden which still has the kroner 25 years after joining the EU.
Ian Blackford, the SNP leader at Westminster, accused Mr Darling of the “same old scaremongering.”
“There is no risk to pensioners, mortgage holders or anyone holding sterling assets or liabilities,” he added.