THE Yes campaign peaked too soon in the referendum battle, allowing Gordon Brown to use "The Vow" to rescue Better Together from potential defeat.

That was the view with full 20:20 hindsight expressed by Alex Salmond last night after his final session of First Minister's Questions at Holyrood, as he shared his thoughts on the campaign that came up short and the remarkable post-referendum resurgence of the party he is handing over to his deputy, Nicola Sturgeon.

With a strange synchronicity, his final interview as First Minister is the last interview conducted by this correspondent after 20 years of covering politics for The Herald.

Mr Salmond does chipper. He does chipper even when things are not. But right now he gives every appearance of leaving on a high, even although his best efforts to persuade Scots to take the plunge into independence came up short. What would he have done differently, what caught him unawares, and what does he make of the aftermath that has seen the SNP more than treble its membership?

"Ten days out we had in our grasp the victory Scotland needed," he says in the ministerial office he will vacate at Holyrood next week, dominated by a Gerard Burns painting titled The Rowan portraying a family carrying a Saltire. Its loan period will end with Mr Salmond's premiership and Ms Sturgeon will have the happy task of finding a new painting for the wall behind her desk.

So what Mr Salmond would have done differently in the referendum campaign was take the lead in the final 24 hours, a refrain repeated by many of his strategists. But this was not to be, with one polling organisation suggesting the lead had been taken 10 days out and this allowed for the final fightback by those backing the Union.

Mr Salmond says he had calculated a response from "The Three Amigos" - Messrs Cameron, Clegg and Miliband - but admits he did not foresee the late role for Gordon Brown in fashioning and pushing "The Vow", which allowed a successful rally for the No vote.

But the outgoing First Minister insists he was not surprised the SNP had been doing well in spite of the No vote in September. "Only in scale, not advent," he insisted, while admitting the party membership growth and the attendances at Ms Sturgeon's speaking tour have been "extraordinary".

He described the independence referendum and the way those engaged with politics for the first time as a life-changing event, "an awe-inspiring part of life's journey." "People have responded to that. For most, the conclusion was not No. It was Not Yet."

He is almost gushing in his praise for his deputy and successor, saying her decision to capitalise on the boom in membership with a huge speaking tour was "spot-on" and saying the event at the Hydro in Glasgow in eight days' time will in effect be a re-convening of this weekend's conference in Perth on a grand scale unprecedented in UK political history.

On how soon another referendum could be held, he is careful to stick to his successor's formula that this would be driven by popular demand and by external circumstances. "Nicola will come to good conclusions, I have no doubt."

But he is clear that post-referendum, Scots remain determined to see change, and the General Election will be the opportunity to put The Vow to the test and ask whether what is being offered is close to federalism, as Gordon Brown promised.

Will he be a participant in that Westminster election? He's still not saying, and will maintain that silence at conference this weekend, but all the body language indicates he'll go for it. "I have made it clear that the only place I would fight is in the north-east," is as far as he will go.