The United Kingdom of Great Britain and Northern Ireland, in case anyone's in any doubt, is a very odd country.

And that oddness, as I was reminded in a recent lecture at, appropriately enough, the British Academy, is centuries old. The historian Davuit Broun unpicked the use of "Alba", the Gaelic name for Britain, to refer to Pictland in an intriguing way.

The Picts, he speculated, might have regarded themselves not only as Britons but true Brits, Britons, as he put it, par excellence, superior to those south of the Forth (the old Scottish border). He concluded by asking whether the quest for Scottish independence should necessarily be understood as a rejection of Britain. Could it not, he suggested, be seen as a reassertion of a particular kind of Britishness?

In that historical context, the SNP's depiction of Scotland as somehow the last bastion of the post-war British consensus, as perhaps more authentically British, has very deep historical roots. It doesn't mean it's true but it's a creative and alluring narrative, just the sort of thing supporters of independence are good at fashioning. Of course, this masks (just about) all sorts of intellectual contortions. In the same breath as advocating independence, Nationalists will argue passionately that, when it comes to currency, energy, university research funding, the monarchy and so on, Scotland and the UK are, ironically, better together. But at least the script is well known: independence is the means to a better end, an independent Scotland will reject the worst of British, and so on.

It gains traction through repetition and, importantly, voters like politicians who believe in things, even if they don't agree. The other side, meanwhile, often aren't very good Unionists. Generally good at casting (often justified) doubt on the detail of the independence proposition, they're less effective at promoting Scotland's place in the Union, particularly in the future. As the Scottish Secretary put it a while back, the No campaign lacks wit and passion.

Which brings me to Alistair Darling, that campaign's figurehead. "The man has never run a campaign," was one Tory's verdict over a good lunch last week. "He is comatose most of the time", a view apparently shared by some senior Labour figures. Calling the former Chancellor comatose is a bit wide of the mark. On the contrary, he's very busy. Recent reports revealed he'd made £170,000 from speaking engagements in the past year alone.

And that might be part of the problem. He looks a bit like a part-time defender of the Union. Initially he was reluctant, telling journalists he'd play a role, certainly, but not actually head up the campaign. Eventually he gave in and has given a perfectly serviceable performance since Better Together launched a year and a half ago.

Watching him the day after the Scottish Government launched its White Paper was instructive. Mr Darling condemned the document's financial calculations but didn't really move the story on. Was he angry about it, he was asked. Yes, he replied, very angry. did he have a vision to match the SNP's? The response, something about enabling everyone to reach their full potential, was oddly perfunctory. Ministers and advisers were at pains last week to emphasise they had no complaints about Mr Darling's performance, but there is unhappiness in some quarters with the wider campaign, and I can't help feeling that includes the Scottish Secretary. "I think that Alistair Darling remains the obvious choice for that job," Alistair Carmichael said rather half-heartedly last week. "I actually think Alistair is doing a very good job."

"What campaign?" someone in the mix asked me with genuine exasperation. "There is no campaign." Better Together is largely reactive, and it seems the UK Government often feels it is plugging gaps that ought to be filled with proactive campaigning. What, meanwhile, is the essence of its case for the Union? "There needs to be a proper script that everyone uses but then why would you want to do the heavy lifting when you can mess around on twitter?" was how it was put.

Mind you, the other Alistair hasn't exactly had a good couple of weeks. Given that the spin accompanying his appointment was that he would take the fight to the Nationalists, for him to be found wanting was more than a little embarrassing. Sure, Nicola Sturgeon aimed some pretty low blows in their STV head to head, but one couldn't help feeling Mr Carmichael was a little out of practice. After all, during three no doubt productive years in the Whips' office he'd rarely had to debate in the Commons, never mind on television.

Naturally, Better Together has pointed to two recent polls, both showing support for independence in the 20s, as proof they've halted the Nationalist juggernaut. But in truth the polls haven't shifted much on either side, so it's tempting to conclude the status quo leads in spite of, not because of, the official No campaign. The same applies to Yes Scotland. Both outfits have barely dented the electorate's consciousness.

Talk of drafting in Jeremy Hunt or Michael Gove is for the birds but there are other Unionist voices in the mix. Douglas Alexander was on more thoughtful form at the weekend and even Robin Harper's recent support for the Union sounded more spirited than his Labour compatriots'.

Gordon Brown, meanwhile, simply makes the same speech over and over again, giving the impression he last thought deeply about Scotland nearly 40 years ago. A short House of Lords debate last week was a case in point. Speech after speech oozed negativity and colourful similes, but forward-looking most were not. Even the noble Lords Foulkes and Steel, believers in some sort of federalism, simply went on the attack. Lord Maclennan at least proposed a UK-wide constitutional convention, while the new Lord Purvis of Tweed alluded to a "refreshed United Kingdom", but in context these were slim pickings. Summing up, Lord Wallace said it was "important that we look to the future" without actually doing so.

Lord Cormack likened Alex Salmond to "a sort of Tartan Boris", and it's not a bad comparison. The Mayor of London, like the First Minister, is comfortable setting out his vision of a more autonomous capital within the UK, something he'll flesh out in a "State of the Union" lecture this evening at the LSE. Indeed, his liberal Tory vision of London - capitalist but fair - isn't a million miles from the SNP's view of an independent Scotland.

Mr Carmichael says: "We can claim the future as well as anybody else," urging his Unionist colleagues to "offer a vision of what it means to remain part of the UK". Perhaps we'll see a little more of that over Christmas, because what the political scientist Richard Rose called "unthinking Unionism" is no longer adequate. "Political authority is not to be won once and for all, like a victory in some distant battle of the past," he judged shrewdly. "Instead, it must be reaffirmed every day."