'What part of No does Nicola Sturgeon not understand?" asked Ukip MEP for Scotland David Coburn yesterday.

The First Minister designate's call, effectively, for a Scottish veto on any UK referendum vote on British withdrawal from the European Union was undoubtedly provocative.

Last night she called for a "quadruple lock" on any decision to leave the EU. If the UK is a "family of nations" then all members of the household should agree, she said, before father takes them on a one-way ticket out of Europe.

Ukip politicians such as Mr Coburn, Tories such as Bill Cash and some Labour MPs were outraged: eyes wide with indignation, like one of those old Bateman cartoons. "A naked bid to federalise Britain," shrieked the Unionist writer Alex Stevenson, as if federalism were a treasonable offence.

At Prime Minister's Questions, David Cameron slapped the SNP leader down, saying: "We are one United Kingdom, and there will be one in-out referendum." There can be no question of Scotland having any right to overrule a vote of the UK people on leaving the EU. The very idea. Get back in your box, you Nats, you ain't going to block no Brexit.

This was all fairly predictable, given the result of the referendum. So what was the point of Nicola Sturgeon even raising it? Well, to make the position absolutely clear that Scotland remains part of a unitary United Kingdom in which Westminster is sovereign. If people in Scotland didn't understand that this was what was meant by voting No, they surely do now.

This clears up the ambiguity about federalism that was left by the referendum. Some politicians, such as former Prime Minister, Gordon Brown, dropped loud hints that, if Scotland voted No, some kind of federal Britain would be the inevitable result.

Scotland, it was suggested, would not simply be absorbed into an incorporating union, it would also have be given an entrenched constitutional status, exercising sovereignty as of right in a quasi-federal UK.

Well, you'll have had your quasi-federalism. Like devolution max, it was, Nationalists can now say, just another Unionist diversion; like Lord Home's call to Scots to vote No in the 1979 devolution referendum on the grounds that the Tories would come up with something better. Of course, they didn't. Who says you can't fool all of the people all of the time?

I can't resist pointing out that I wrote a column in this space before the referendum saying: "There isn't a cat in hell's chance of federalism if Scots vote No." I was taken severely to task, not least by my good friend and colleague, David Torrance of this parish, who said: nonsense, how quaint and old-fashioned you are. Of course federalism is coming, he said. Why, it is almost here already, with Westminster evolving into a federal structure and happy, devolved parliaments like Holyrood exercising sovereignty in a new federal UK. Gordon Brown's book My Scotland; Our Britain is a blueprint, said David Torrance, for "federalism in all but name".

Well, I think we can all agree that it wasn't. The doctrine of Westminster sovereignty is back and it's proud. No means No. If Scotland had, indeed, been in a federal or even quasi-federal status in the UK, a big constitutional decision like membership of the EU is precisely the kind of existential issue it would have expected to have a say on.

In countries such as the US or Canada there are mechanisms for states or provinces to block certain constitutional changes. They can do this because, in federal systems, provincial parliaments exercise sovereignty (or power ,which is what sovereignty means) in their own right. This cannot be taken away.

In the UK system, under the gospel according to AV Dicey, the Victorian constitutionalist, sovereignty is something only Westminster can exercise. It is a semi-mystical quality and indivisible. This is why Britain has no written constitution. Westminster's power is supposedly infinite and without limit; except, confusingly, that it actually is limited.

The Northern Ireland Act in 1998 gave the people of that province the sovereign right to decide their own future and to leave the UK if they weren't happy with the way Westminster was exercising its God-given sovereign power. This means that Northern Ireland does have a say on whether it leaves the European Union if Britain decides to rush for the exit in David Cameron's in-out referendum in 2017.

Northern Ireland is much closer to the Republic of Ireland today than it was during the Troubles. It has no border, and there is in an effective currency union with the Republic.

If Britain leaves the EU, and David Cameron erects borders, a lot of people in the province may want to exercise their sovereign right to have a vote on it: a binding one. And the Northern Ireland vote will be decisive because they have the option of joining the Republic of Ireland and leaving the UK.

The situation is more difficult in Scotland because we don't have the escape clause. There is no mechanism for a region like Scotland, however it voted, remaining in the European Union if the nation state of which it is a part leaves.

This is why the First Minister-designate is saying that Scotland should have a right, effectively, to veto the UK referendum vote.

As things stand, Scots are more pro-European than are English voters. About 50 per cent of Scots say they want to remain in the EU against about 35 per cent who want to leave. In England it is the other way round. This drops a federal hand-grenade into the middle of the Smith Commission, which is grappling with honouring the "vow" on more powers for Holyrood, including a statement on the constitutional status of the Scottish Parliament.

The parties are said to have largely agreed on this already and are moving on to look at the "extensive new powers" Holyrood is supposed to acquire. But it is most unlikely that the Scottish Parliament will have a keep-Scotland-in-Europe clause or a declaration of federalism.

This is unfortunate, not for the SNP but for the UK. Federalism is the only option that could, in my view, resolve the Scottish question for a generation. It would allow Scotland home rule on its domestic economic affairs while remaining in the UK.

The categorical rejection of federalism yesterday will fuel the anger of those many Nationalists who believe the referendum was a con.

It also becomes an issue in the Scottish Labour Party leadership contest, into the ring of which Labour's Scottish health spokesman, Neil Findlay, has just thrown his hat. Mr Findlay is a member of the Red Paper Collective, a left-wing Labour ginger group. It supports federalism.

And so does Carwyn Jones, the Labour First Minister of Wales. It will be fascinating to learn what Mr Findlay has to say on this, and also Jim Murphy if, as expected, he today becomes the third candidate for what some are calling the poisoned quaich.