91�ȱ�

This week's battle of Britain began with an argument about the date of a referendum on Scottish independence. It is quickly turning into one about the question to be asked.

Senior government sources have told me that, despite the talk at the weekend of the need for a vote within 18 months, they can live with Alex Salmond's proposal for a vote in the autumn of 2014.

What they really care about is ensuring that there is only one question - a simple Yes/No to independence - and not a second vote on "devo max" or what some used to call "independence-lite".

They are delighted that Salmond felt the need to rush out a date and that he plumped for one before the next Westminster elections.

Their fear was that the Scottish Nationalists would play this long and at least until after the next Westminster elections in 2015 when there might be another Tory-led government.

They are determined that Salmond will not be allowed a "fall-back" option of greater powers for the Scottish Parliament if he loses a vote on independence.

This is part political calculation and part principle.

The new coalition for the Union of the three major UK parties argue that a fundamental change to the position of Scotland within the UK - for example, much greater tax and spending powers - would have implications not just for the Welsh and Northern Irish assemblies but all parts of the UK.

In other words, that option is not one for Scots alone to decide on.

It's all rather curious since the signs are that Labour and the Lib Dems are moving towards the idea of much greater powers for Holyrood.

It raises the possibility that Salmond may fight and lose an independence referendum but end up as first minister in a more powerful Scottish Parliament.

That is the view of Sir John Elvidge who was, until 2010, Salmond's top official - permanent secretary of the Scottish government - who was one of those who took part in the Decision Time programme I chaired on 91�ȱ� Radio 4. You can listen again here.