Vow delivered or veto imposed?

David Cameron was in Scotland today to meet First Minister Nicola Sturgeon. Photo: Andrew Milligan/PA Wire/Press Association Images

The pre-referendum vow of more power for the Scottish Parliament fulfilled?

Or a Westminster veto imposed on Holyrood?

That in a nutshell is the question sparked by the publication today of draft legislation to implement the recommendations of the cross-party Smith Commission.

Lord Smith of Kelvin headed the Commission. Credit: Andrew Milligan/PA Wire/Press Association Images

The UK government from the Prime Minister - in Edinburgh today - down, say the Unionist parties have kept their pledge.

The Scottish National Party government say they have done nothing of the sort.

The nub of the argument is welfare powers.

According to the draft legislation, if a Scottish government wanted to make changes which impacted on - say -Universal credit, Whitehall ministers would have to be consulted and "give his or her agreement".

Case proved say the SNP. It's a veto.

Not so say UK ministers.

The draft goes on to say "...such agreement not to be reasonably withheld".

Now the fact is there are huge areas in the draft legislation which will give more powers to Scotland.

And which the SNP will accept. But they will also keep emphasising the "veto".

They have a UK general election to fight and this fits what political types call the nationalist 'narrative'.

Polls suggest the SNP will do very well too in May.

So on a day when the UK government hoped to seize the initiative they have been forced to answer questions on the details.

They wanted the debate to be not about even more powers or disputes about power but about what Scotland did with those powers.

Danny Alexander. Credit: Daniel Leal-Olivas/PA Wire/Press Association Images

Their answer, has been given by Danny Alexander the Treasury Chief Secretary.

No ifs, no buts, he says, there is no veto. If they can pay for it, a Scottish government can do what it wants with the new benefit powers it is getting.

And now, please, he is effectively saying, let's debate what to do with those powers.

Who wins this latest battle for Scotland will have a substantial impact on that election in May.

And, therefore, on who governs the UK.