You might remember that a week ago, following George Osborne’s ludicrous statement that Tony Blair ‘achieved nothing’ in ten years in power, I reeled off some of the facts that negated his view.

I also noted that so far, there was little by comparison that the Cameron government could put down as historically equivalent to Bank of England independence, the Good Friday Agreement and all that followed, the minimum wage, Sure Start, civil partnerships, the end of Milosevic, and of Saddam, the biggest hospital and school building programme since the foundation of the welfare state, the smoking ban, the boost for aid in Africa, record levels of literacy and numeracy in schools, paternity leave, winter fuel payment and free TV licences for pensioners, the cleanest rivers, beaches, drinking water and air since before the industrial revolution, free breast cancer screening for all women aged between 50-70, the New Deal which helped over 1.8 million people into work, free entry to national museums and galleries, reduction in heart disease deaths by 150,000 and cancer deaths by 50,000, a cut in long-term youth unemployment by 75 per cent etc etc etc.

David Cameron, did I read rightly the other day, is the third longest serving Tory leader of the last century, behind only Churchill and Thatcher.  I think if students of history were asked to write essays on the historic achievements of these three, they would not struggle at all with Churchill, Thatcher would provide plenty of material, whereas for Cameron it would frankly be a bit of a struggle. Imagine being asked to do 1000 words on each. For Churchill and Thatcher, it would be hard to squeeze it all in. For Cameron, fittingly, waffle would be required.

I think the student would be left with the single fact of leading a coalition, itself of course a product of political and strategic failure to win an election when it was frankly there for the taking.

There is now, after today’s events in Edinburgh, the possibility that his greatest historic significance will be as the Prime Minister in office when Scotland broke away from the rest of the UK.

I still think it unlikely that Scots will go the whole hog and vote for independence. But whereas when the Scottish Parliament was set up (another major achievement of the Blair government, Gideon) I would have said it was unimaginable, now at least it is possible to see that it might just happen.

Much as I hope that it doesn’t, the world of politics and economics are in such a state of flux that frankly anything could happen.

At least now the campaign can get seriously underway, and the difficult questions Alex Salmond has so far managed to avoid can be put with vigour.

Let battle commence. And let all who believe we are better together hope that Cameron does not find his place in history as the leader of the Conservative and Unionist Party on whose watch the Union fell apart.