Scottish independence could break the "social contract" that holds British communities together, Gordon Brown warned last night in his first public intervention in the referendum debate.
The former Prime Minister, who has stayed out of discussions about Scotland's future since he left No 10 in 2010, used an appearance at the Edinburgh Book Festival to throw his political weight behind the unionist cause. He challenged the Scottish nationalist leader Alex Salmond's oft-repeated assertion that Scotland would retain its social union with the UK after independence. This would not happen, Mr Brown declared, because, in leaving the UK, Scotland would be breaking the social contract which the constituent parts of the kingdom had forged together.
He said: "I suggest that if through some version of independence we break this apart and set nationally or regionally varied minimum pay rates, nationally varied corporation tax rates and nationally varied social security rates, we will start a race to the bottom under which the good provider in one area would be undercut by the bad and the bad would be undercut by the worst.
"Modern Britain is founded on something more important than old sentiment, self interest, temporary advantage … but on shared values – and that these values have not only shaped the Britain we know but can shape the multinational arrangements of the future."
In a highly intellectual speech, he showed his determination to help the cross-party anti-independence campaign led by Alistair Darling in its fight with the nationalists.