The Treasury have firmly denied the story, and I'd certainly be surprised if we saw significant delays in the cuts. For starters, it would undermine the coalition's argument just as they've hit on a good one: that paying out £120 million a day in debt interest payments is a moral, as well as a fiscal, failure. And it would also be a gift for Labour and their new shadow chancellor. Ed Miliband & Co. would be able to claim, albeit disingenously, that the coalition had followed their advice to restrain the axe – and that a double-dip had been avoided for that reason.
But I suspect that the FT story does reflect some concern about the cuts along Whitehall – not so much about their scale, but about their practicability. Some civil servants mutter that the various "efficiency savings" and "administrative costs" may not add up to all that, or may take a while to seep through the system. The end result, they claim, may be lower cuts in practice than the Budget accounted for in theory.