caused uproar last year when he dismissed the opening of the Scottish Parliament as Tony Blair's "biggest mistake".Devolution - which meant power was taken from Westminster and handed to devolved governments in Edinburgh, Cardiff and Belfast - was a key policy introduced by the New Labour government in 1997.It was bitterly opposed by many Conservatives at the time and suspicion has lingered that Boris Johnson remained against it.But the Tory leader has now rowed back on his comments and insisted