The so-called Spin Room at Glasgow's Royal Conservatoire was packed at the start of the Scotland Decides debate.

The Yes table was composed of stars such as Pat Kane, Tasmin Ahmed Sheikh and Blair Jenkins who were enjoying themselves hugely, taking selfies and generally owning the room. The No table, by contrast, looked subdued and slightly edgy. Two hours later, the tables had turned. Yes took to an anxious-looking huddle, while the Nos erupted in somewhat bewildered jubilation. Had their man actually won the debate?

Well, the press corps' verdict was pretty much unanimous: Darling had won hands down. Expectations for the former Chancellor had been so comprehensively lowered that he was assured a good press. But Yes supporters such as Lesley Riddoch were of the same mind. It was not the First Minister's best night.

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In pure debating terms, Alex Salmond was the least convincing of the two, seemingly lost on issues such as the future Scottish currency if Westminster carries out its threat to deny Scotland use of the pound after independence. His attempts to sound statesmanlike came over like complacency. And the jokes about Unionists claiming an independent Scotland would be vulnerable to alien attack were unfunny and patronising to viewers. Wit isn't the word that immediately comes to mind when hearing the former Chancellor but even Yes supporters smiled at some of Darling's comebacks: "You're more like Michael Howard than Jeremy Paxman, First Minister".

By the next morning, Team Salmond was heavily into damage limitation mode. The First Minister arrived at the Business for Scotland conference in Edinburgh's Dynamic Earth armed with polling figures from the Guardian ICM snap poll apparently showing that his performance had been a modest hit with the voters, if not the journalists.

Yes support had risen two per cent in the two hours he was being pummelled by Mr Darling's fickle finger of hate. ICM ended the night with the score on a binary basis at Yes 47 per cent and No 53 per cent. This was, Mr Salmond boasted, the highest support for independence since the 2011 election. I'll leave Professor John Curtice to make sense of that, and the claim that the biggest increase in support was among women and undecided voters.

However, it would not be the first time that an apparent debating victory turned out to be less convincing in the cold light of day. Alistair Darling did a convincing impression of Mr Angry, ranting and jabbing a loaded finger at his opponent. Normally this is a total viewer turn off as voters generally don't like aggressive adversarialism.

The Better Together chairman's case was unapologetically negative. He seemed almost physically averse to the suggestion that Scotland could be a successful independent country, a proposition that even David Cameron accepts. Mr Darling was unconvincing on what new powers the Scottish parliament might enjoy after a No vote, becoming tongue tied and incoherent on taxation.

But his barracking on the currency, though crude, prevented Mr Salmond from articulating his vision of a wealthy, healthy, egalitarian Scotland taking charge of its own destiny. This can't go on.

So how does the Yes campaign dust itself off and get back in the independence race? At root the problem is still the pound. Better Together's campaign is essentially a singe-issue one, certainly since February 13 when George Osborne delivered his infamous Declaration on the Pound. The Tory Chancellor said he would erect a financial Hadrian's Wall to prevent Scots using sterling, thus damaging the Scottish economy.

Alex Salmond insisted on Tuesday that the pound is as much Scotland's property as England's, which it is. The pound was the prime economic expression of the 1707 Union, which was supposed to be a partnership of two free nations. The idea that the pound is England's property to be taken away if Scotland doesn't behave is hardly in the spirit of the Union.

But Scots have never trusted the UK to play by the rules. Most voters probably accept, intuitively, that the pound threat is bluster. "Economic vandalism" as Anton Muscatelli, the Vice-Chancellor of Glasgow University has described it. But voters can't be sure vandals aren't in charge of the UK Treasury. No-one can be 100 per cent sure that Westminster wouldn't behave so spitefully after a Yes vote that it would damage England's economy in order to punish the Scots.

Mr Salmond's refusal to contemplate alternatives to a currency union is understandable. As soon as he suggests that Scotland would adopt its own currency, he'll be accused of turning Scotland into a banana republic; like, ha, ha, Panama or Argentina. In fact, as this column has argued before, there is no reason to be afraid of Plan B.

Lots of very successful countries have their own currencies, such as Denmark, Norway and Switzerland. Anyway, as the First Minister told the Business for Scotland conference yesterday, somewhat belatedly, no-one could stop Scotland using the pound if it wanted to.

After independence, Ireland issued its own pound, on a one-to-one parity with sterling, and as a result UK pounds continued to circulate in the Republic for 50 years until it joined the European Monetary System. Mr Salmond cited Hong Kong as a country that has done well shadowing the dollar.

There are so many positive examples to choose from that you wonder why Mr Salmond has been so reticent about Plan B; and so shy about turning the fiscal tables on Westminster. For, as he also told business supporters yesterday, if the UK blocked a currency union they could not expect Scotland to accept its liability to a per capita share of the UK debt mountain, around £110 billion. Independent Scotland would, Mr Salmond said, get off "scot-free", saving almost as much in debt interest repayments as current North Sea oil revenues.

Unionists claim that if Scotland "reneged", international financiers would increase the interest rate on Scottish debt, at least in the short term, because of uncertainty about whether it could be trusted to repay. But since independent Scotland would have very little debt anyway carried over from rUK, a few points extra would not be crippling in the short term.

Scotland is not Greece. GDP and productivity in Scotland are equal to that of the UK. Scotland has substantial hydrocarbon and renewable assets, five world-class universities, a thriving food and drinks industry and considerable strengths in life sciences and financial services. Whisky exports alone are worth £2.73 billion a year. For a country of five million people, this is pretty healthy.

Meanwhile, the rUK would be saddled with exclusive responsibility for paying off the massive debts which have been accumulated by successive Westminster Governments, without the cushion of oil revenues.

It's not very neighbourly or friendly. But the Scottish Government has insisted all along that it is prepared to pay up so long as Westminster plays nice. And if Westminster wants to fight dirty, well, Scotland can do the same.

I dislike boxing analogies but the First Minister has for too long had one hand tied behind his back. Next time he should come out fighting.