SO far, it's all been a bit Disgusted, Tunbridge Wells, like those letters to Points Of View demanding to know why (oh, why) there are foreign imports on TV.

The indignation is real enough; the signs that Outraged of Uxbridge has thought the matter through are few.

The Scottish National Party is doing well. Instead of the usual taxi, its MPs will soon need a team bus. Estimates of the exact number of seats it can expect vary, but no-one argues over a single word: dozens. With Tories and Labour neck and neck in the polls, realisation has crashed like a cold wave over the heads of those who barter opinion in the London media: those Nats could decide, well, just about everything.

In one of those mature democracies you hear about, this would have troubled no-one. Such is the nature of a parliamentary system with a first-past-the-post rule that has, until now, suited the beneficiaries just fine. The Better Together campaign used to do a lecture on the subject. Any Scot who grumbled about being stuck with governments England had chosen was reminded of how things work. Those are the breaks, they said.

In that same late-summer period last year, stalwarts fighting for the Union also spent time, money, airtime and newsprint trying to give Scottish voters a warm glow. They loved us dearly, and they weren't afraid to say it. Stay, they said. Please don't go, they said. Remain as valued partners in the great enterprise of Britain.

Was it just six and a bit months ago? A majority chose the Union and then turned their attention to picking candidates and parties for election to the parliament shared by everyone in the UK. Meanwhile, SNP membership shot up along with the party's poll ratings. That was OK, wasn't it? That's how things are supposed to work, isn't it? Wasn't that what Unionists wanted?

Instead, just lately, a lot of coverage has seemed to suggest that if the SNP isn't a proscribed organisation, it jolly well should be. Last Tuesday, a former First Minister gave an interview to New Statesman magazine in which he restated familiar positions. There would be no negotiations with the Tories. Instead, the SNP would vote against a minority Conservative government at the first opportunity, probably on the occasion of the Queen's Speech.

That's just the nature of the Westminster game, you might (rightly) have thought. Conservative Campaign Headquarters instead tweeted: "Salmond has confirmed he would sabotage the democratic will of the British people in order to make Miliband Prime Minister." Grant Shapps, Tory chairman, elaborated, claiming that Salmond was "threatening to undermine a government chosen by the British people".

An inept animation had already been released showing Ed Miliband dancing to the SNP piper's tune, but that was, in election terms, nickel and dime stuff. Portray your rival as weak, beholden, desperate for support - and distract attention from the fact that the Tories are, if anything, in a worse position. Here, however, was a twist.

Despite the fond words of Better Together, a distinction was being made between "British people" - the phrase was not employed twice by accident - and any supporter of the SNP. Such individuals were something else again. Beyond the pale, you might say.

By this reckoning, amplified across the London press, the Nationalist party counts as an alien and illegitimate force. It has no right - as simple as that - to decide the fate of Westminster government. But given the SNP's popularity, this is also a judgement on people as well as a party.

The Scots are perfectly tolerable within this British Union, it turns out, but only if they mind their place. The idea that English people might wind up with a government they didn't vote for is - now imagine that - an outrage. And by these means David Cameron means to hold together the Union that was, not so long ago, so dear to him?

Right-wing journalists have been quick - the scandal - to put party before country. So we've had Max Hastings in the Mail averring that: "There is nothing David Cameron can promise the Scots that will bring them to their senses." We've had Iain Martin, Telegraph blogger, reporting that "in England more and more people I encounter just want the Scots, or the Scottish Nationalists who shout loudest, to stop whinging and whining".

Out of their senses, whining like children, and all because votes cast in Scotland might for once make a difference? All that Salmond and Nicola Sturgeon have actually said is that the SNP could probably support Labour on an issue-by-issue basis. Naturally, they think they'll do a better job of holding Miliband to a few principles than Scottish Labour has ever managed. This is presented as the height of insanity, or worse.

Last weekend, the Tory defence minister Anna Soubry sat on the sofa offered by the BBC's Marr Show after Salmond had been interviewed. Her response to the former First Minister was fascinating. Soubry said: "The thought that we are in a position where you could be actually controlling, in the way you have described, this United Kingdom fills me with absolute horror. The audacity is astonishing."

It wasn't clear if the minister meant Salmond, the SNP, or anyone supporting them. It could have been a Sun editorial. Last week, an example of the genre said that "English voters will be in uproar" over the possibility of Nationalists keeping Miliband in office. "If the Tories cannot get the votes to stop them ruling the roost down here, we are in for five years of mayhem and misery." Strangely (or not), the Scottish edition arrived at an entirely different conclusion.

The signs are there will be a lot more of this to come after Parliament is dissolved tomorrow and the official election campaign commences. Not least of the spectacles will be further hysterical attempts to turn English opinion against all those Scots who persist with the SNP. The compass has been reset: north is central. Our votes are at the heart of the matter for Tories attempting to snuff out Miliband, for Labour attempting to cling on in Scotland, and for anyone - meaning everyone - still wondering how the a Westminster government will be formed.

Scottish Nationalism won't get much help from the BBC. The clue, as ever, is in the acronym. The issue here is not the overt party bias that comes as second nature to the Telegraph, Mail and Sun. It is partly to do with an institution's role within the Unionist state, partly the BBC's belief in what seems, especially from London, to be the natural order of things. Its journalists have been as astonished as any by the thought that the SNP, a party of the regions, could hold the balance of power at the heart of the UK.

That, though, is the betting. The possibility not yet considered by Confused of Chelmsford is that Scottish Nationalism could be influential at Westminster for a long time to come as formerly "big" parties shrink. If that sounds like a problem there is, of course, a solution open to England's politicians.