WELL that was brutal.

Watching George Osborne, the Chancellor, deliver a Thatcheresque "no, no, no" to a currency union between an independent Scotland and the continuing UK was not for those of a nervous disposition. It is all turning a bit Tammy Wynette, D.I.V.O.R.C.E, out there, is it not?

The Yes camp has always been keen to put a D notice on any mention of the D word, conjuring up as it does the possibility of the party initiating the split ending up in a worse position, despite all the upheaval. For the same reason, Mr Osborne, the most nakedly political chancellor since Gordon Brown, has chosen to frame the matter in precisely those terms.

The pound, said Mr Osborne in Edinburgh yesterday, was not an asset to be divided up like a CD collection. If Scotland walks, it is not taking the pound, or ABBA's greatest hits, with it. There was a certain grisly inevitability to this issuing of a lawyer's letter.

Consider the process so far. We have been through the "it is not you, it is us" stage. Sad smiles have been exchanged, memory lane walked. There has been talk of a bright new future for one party and, in time, the other side will see that really, truly, they are better off as well. It has been human interaction at its most civilised and mature.

But now the other side has had time to think, to consider what all this freedom on one side will mean for it. A sense of injustice has crept in, irritation even. Mr Osborne, selfless soul that he is, has opted to express those feelings on behalf of what he sees as the so-far silent rUK majority. Leaving aside the obvious appeal for Tory votes, one wonders if he is not right to do so. Does Scotland overestimate the rest of the UK's willingness to keep us sweet and send an independent nation merrily on its way? On the evidence so far, yes.

In Scotland there was perhaps inevitably a hostile reaction to the Osborne-led intervention of the three main UK parties.

Laughably, the online version of Treasury paper listed the ministerial sponsors as the Rt Hon Danny Alexander MP "+ two others", who turned out to be Alistair Carmichael, the Scottish Secretary, and Mr Osborne. As if the top billing for a Scot would take the razor sharp edge off what was to follow. According to an accompanying letter from no less a personage than the permanent secretary to the Treasury, Sir Nicholas Macpherson, a currency union is a non-starter. It would be bad for Scotland, by leaving it with a reduced ability to react to events, and bad for the continuing UK, by exposing it to increased risks. In other words, words which the pukka Treasury would never use, the idea of a currency union, as set out in the Scottish Government's White Paper, was an attempt to sell the rUK a pup. Up with this, voters outwith Scotland could not be expected to put.

Of course it was an attempt to intimidate, but that does not mean it can be ignored. Scotland has been living for so long with the independence question that we fail to realise that what is important to us does not amount to much in the way of a hill of beans in other countries. Since 2011 in particular we have been a nation in a bubble. It has been all about us. Other matters, both domestic and at UK-level, have languished outside that bubble. That those in other parts of the UK would at some point realise that independence for Scotland might have implications for them, and that their political representatives would start to voice concerns, was a matter for another day. That day arrived yesterday.

As any visitor to the rest of the UK knows, Scottish independence ranks well down the running order of interests. Or at least it did. What Mr Osborne's intervention aims to do is turn the political matter of Scottish independence into a personal, financial one for the rest of the UK's citizens. He is bringing it to their doorsteps. Previously, the way was left clear for the Yes camp to reassure the public on both sides of the Border that it would be in the "overwhelming interest" of all to forge a currency union. Forget that, says Mr Osborne, it would be a dodgy deal for both Scotland and the rest of the UK.

That he ultimately cares more about any potential risk to voters in England than he does Scotland's financial future is neither here nor there. The same goes for the motivations of the Labour Party, which sees its Westminster seats disappearing, and the Liberal Democrats, who would frankly sell their granny and her slippers to stay in power. That is the way it is. As Ed Balls, the Shadow Chancellor, put it, "Welcome to the real world."

We might bristle at the manners of Osborne, Alexander and Balls - they even sound like a legal firm, don't they? - but once over this we might reckon that they have done the independence debate a favour.

It was always a nonsense that Scotland could ease gently into a currency union simply and largely because it is the second largest export market for the rUK. As the Treasury paper points out, there are many other factors to be considered, such as who or what should be expected to smooth out the bumps if there was a plunge in the oil price, or a financial institution in crisis.

There are plenty of questions, and it is time the Yes camp started providing better answers than they have so far. The holding position in the White Paper - "We propose that the pound Sterling will continue to be the currency of an independent Scotland" - will not hold any more. The Scottish Government has proposed, the UK Treasury has said no, so what is next?

For all its finality, there is good reason to suspect that what happened yesterday was a negotiating tactic, a salvo from the same party that brought you "Labour's Double Whammy" and "Labour Isn't Working" posters. Even if it is not, why should Scotland care if feathers are being ruffled in the rUK? Is that not in some strange way a sign that independence is worth fighting for? After all, no-one battles to keep something that is of no use.

But whatever the outcome of the vote, this whole process is one of negotiation, and negotiation is built around the principle of quid pro quo. The Yes camp wants the quid. What they are offering in return amounts to little or nothing in the Chancellor's eyes. While he will never be convinced otherwise, it is not him who has to be persuaded come September 18. In answering the concerns of the rUK - anxieties that will only heighten from this point - the Scottish Government will also be addressing the real fears of many Scottish voters. It is better to know now if it does not have those answers.

When not singing about divorce, Tammy W was one for standing by her man. It is time, First Minister, to explain how you will stand by your plan.