With the 700th anniversary of the death of William Wallace looming, Scots are preparing for a festival of misty-eyed commemoration. However, one of Scotland’s leading historians is about to spoil the party by claiming that the country’s greatest nationalist icon could equally be regarded as a unionist hero. Professor Tom Devine will argue that Wallace’s reputation has significantly changed over the centuries and that middle-class Victorians viewed him as responsible for the Union of 1707.

Devine’s intervention will anger nationalists, who have accused the Scottish executive of not doing enough to honour his memory. Earlier this month, Alex Salmond called for the Scottish flag to be flown from every public building in the country to mark the 700th anniversary of Wallace’s execution.

Wallace — whose story was popularised in the 1995 film Braveheart, starring Mel Gibson — is chiefly remembered for his victory over English forces at the battle of Stirling Bridge on September 11, 1297.

Devine, who will present his theory this week at the inaugural Festival of Politics at Holyrood, said the Wallace story was “malleable”.

“I think the problem is this, ever since Braveheart and ever since the view that Braveheart actually was a factor in devolution, he’s been regarded as a nationalist icon. You could say the nationalists have hijacked him, but that’s no different from what happened in previous ages,” he said.