It was a classic example of news management.

In the run-up to his debate with Alex Salmond, supporters of Alistair Darling were excessively modest about their man's chances, and nervously declined to predict who would be the winner.

Supporters of the First Minister, meanwhile, fell into the trap of declaring victory too soon.

SNP MP Pete Wishart foresaw "a slaughter worse than the Bannockburn re-enactment" held to mark the battle's 700th anniversary in June while one Yes-friendly columnist stated as fact that Darling "will never better" Salmond.

Both approaches made Darling's unexpected performance look all the more spectacular on the night - and Salmond's all the more abject.

A former advocate, Darling was keenly aware of the importance of being well-prepared.

Aided by four Better Together researchers and a "debate camp" team of half-a-dozen spin doctors, he went into training for more than a week at the No campaign's HQ in Glasgow, then for the last weekend at his home in Edinburgh.

He asked his researchers for material on dozens of possible topics, then fielded rapid-fire questions from his team to hone his presentation.

"He tends to give long answers to questions," said one No camp insider. "We didn't want that. We wanted short answers."

Darling also decided in advance that he would pursue Salmond as hard as he could on a Plan B for the currency under independence.

Besides being home turf, it was also the issue he had been convinced from the outset would come back to plague Salmond and the Yes camp. "I did what any good lawyer does, I kept asking him," Darling explained afterwards.

Because they speak in numbers, most chancellors develop a reputation for dullness.

So his animated performance caught Salmond on the hop.

But Darling told the Sunday Herald it was not the product of debate training, but simply reflected the passionate person within.

"I'm a naturally restrained, quiet person. But this is something I care about. I came off the backbenches to do this campaign because I care passionately about what happens to my country.

"On Tuesday night I was passionate about it because I am passionate about it."

Perhaps most worrying for the Yes side is that last week revealed Better Together are working to an long-term "grid".

Unionists agreed months before George Osborne's announcement in February that they would refuse to entertain a currency union. The morning after Darling made it the story of the debate, Labour campaigners were on the streets handing out golden circular flyers of a pretend pound coin bearing Salmond's face.

"Don't bank on Salmond. Keep the UK - Keep the pound," ran the motto round its rim.

The following day, Labour took a giant version of the pound to the First Minister's official residence, Bute House, for a photocall.

This shows Better Together have a tight plan and they are executing it efficiently to deny the Yes side any sense of momentum.

For now, Yes strategists are taking comfort from polling suggesting Darling's approach did not win over female and undecided voters, and say the media called the debate wrong. "The media love blood and guts in a debate, but the public don't," said one Yes insider.

"Alistair Darling may get plaudits from journalists, but he hasn't found any great favour with the general public."