There was little room for serious doubt.

First: "A vote for No is not a vote for 'no change'." And then: "Giving the Scottish Parliament greater responsibility for raising more of the money it spends - that's what Ruth believes and I believe it too."

A reasonable interpretation of David Cameron's speech yesterday at the Scottish Tory conference was that he was giving his firm backing to more powers for the Scottish Parliament in the event that Scots vote to stay in the UK. There was some speculation over his use of the word "can" when he said "vote No - that can mean further devolution, more power to the Scottish people and their Parliament but with the crucial insurance policy that comes with being part of the UK", but his aides later stressed that this meant "will". He had used "can" to seem less pushy and presumptuous.

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We shall see. Deputy First Minister Nicola Sturgeon claimed the Prime Minister had "torn up any prospect of a meaningful offer of further powers to Scotland" but, according to Mr Cameron, that is not the case. Detailed proposals from the Conservatives' commission on further devolution will be published in May, but the Prime Minister has made clear he would back further change, including the ability to raise more tax.

Just after Christmas, Ms Sturgeon called upon the pro-UK parties to spell out what a No vote would actually mean. This has long been one of the unanswered questions voters have had to grapple with and it is right that greater clarity is demanded of the three pro-UK parties. Those answers are emerging. Following on from similar pledges by the Liberal Democrats and Labour, the Prime Minister's promise on behalf of the Conservatives suggests that further devolution will result if Scotland votes to remain in the UK.

Inevitably the promise of new powers begets more questions. Can the Prime Minister be trusted? Pro-independence campaigners raised the fear yesterday that he could not but, having made such a highly personal, passionate speech in which he promised further powers for the parliament, he would risk denting his credibility and inflicting serious damage on the Scottish Conservatives were he to renege.

What sort of devolution? How far would it go? The three parties will offer a spectrum of choices, with the LibDems (who have already published their proposals and want MSPs to be able to raise 60% of the money they spend) probably going furthest; the Conservatives likely behaving true to form by being the most conservative; and Labour somewhere in between.

Which plan will prevail will be influenced by who wins next year's General Election. Where all agree is that further tax-raising powers should be transferred to Holyrood, a significant enhancement of its powers which would make MSPs more acountable for the money they spend.

Polls show a greater number of Scots favour stronger devolution than either the status quo or independence yet, naturally enough with the referendum approaching, all the talk is of independence. It may eventually prove that the emerging discussion of stronger devolution turns out to be the one that really counts.