CIVIL war erupted in the Scottish National Party at the weekend. Mock reports, illustrated with photoshopped visual gags, appeared all over Twitter and Facebook, listing casualties in the Battle of Glasgow Green, the Siege of Leith and the Assault on Lorne (sausage). There were accounts of atrocities in Greggs. The Nationalists have discovered that humour is a more effective weapon than abuse in their battle with the “Yoons”. They simply laughed off media reports that the party had split over the fate of Alex Salmond.

I am not and never have been a member of the Scottish National Party, but I’ve no difficulty believing it to be the most extraordinary phenomenon in British politics, not least in its preternatural ability to unite in the face of adversity. Other parties are becoming virtuosos in the art of political division. The Conservatives are split at least three ways over Brexit, with their Prime Minister’s authority in ruins and Boris Johnson in open revolt. Labour is bitterly divided over anti-Semitism and Jeremy Corbyn’s leadership. The SNP isn’t: it realises that unity works.

With 125,000 members, the SNP is now the second largest party, not just in Scotland, but in the entire UK. Indeed, if the SNP membership were scaled up to UK level, it would have twice the UK Labour Party membership and 12 times that of the Tories. Such numbers might be expected in a radical opposition party, but not a long-in-the-tooth party of government.

Yesterday, Nicola Sturgeon announced the 12th legislative programme since the SNP entered government in 2007. The SNP is now into its second decade in office, yet support appears actually to be rising again, according to YouGov, and is back to 40 per cent. This despite the widely-publicised problems with NHS waiting lists and poor performance in educational league tables. Nor has support for independence flagged, with one poll this week suggesting that, if Brexit happens, more Scottish voters are minded to support Yes than in 2014.

Ms Sturgeon appears to have seen off the threat from Richard Leonard’s newly-Corbynised Scottish Labour, and we are reliably informed that Ruth Davidson is now looking to a political future in Westminster. Much of this success is down not to the Scottish Government, which has made its share of mistakes, but to the resilience of the party itself. Yesterday’s programme was a workmanlike job with important measures on mental health, animal welfare and children’s rights, but it was essentially an addendum to last year’s offerings on tax and the environment. Everyone says Ms Sturgeon’s administration is looking tired, and in some respects it is. Truth be told, the Scottish Cabinet, Sturgeon aside, has never looked particularly dynamic. But the slide to political disfavour, widely predicted after 2017’s abortive referendum, hasn’t taken place. The party continues to break all the established rules of politics – the pendulum refuses to swing. This is largely because the SNP membership has turned party unity into an article of faith, and turned positive thinking to a potent political weapon.

It’s not as if the SNP lacks issues to split over. There’s Brexit for a start, upon which there are widely differing views. Some back Brexit, some back a People’s Vote against it, most are dismayed at the prospect and feeling powerless.

Ms Sturgeon can’t make up her mind on whether to support a People’s Vote, but unlike in the other main parties, no vociferous factions have emerged to persuade her either way.

Many SNP activists are desperate for an early independence referendum, and believe that if Nicola Sturgeon doesn’t announce one now, the chance might never come again. We have pro-independence marches wending through Scottish cities almost by the week. But Ms Sturgeon has pointedly declined to endorse them, and has given precious little sign of being about to call a referendum. In any normal party, there’d now be two warring camps, like the Leavers and Remainers of Brexit, on this existential question of independence. But not the SNP. You can almost sense it positioning itself for constructive disappointment, not open revolt. The great split over the referendum may never come.

Then there’s the Sustainable Growth Commission Report,with its dismal science of deficit reduction. That caused much dispute on the Scottish left, but the membership has refused to turn it into any recognisable left-right division in the party. There’s no Campaign for SNP Socialism. The will to unity is just too strong – as it has been in the backwash from the resignation of

Alex Salmond – a veritable god in the Nationalist pantheon, who has been cast out of the party after over 40 years.

The row over Mr Salmond’s crowdfunding took place outside the SNP. Faced with the extraordinary prospect of the former First Minister taking the Scottish Government to court, SNP members refused to turn what they see as a personal drama into a political crisis. Many SNP women have concerns about victims of sexual harassment, and Mr Salmond isn’t universally popular, but they chose not to turn this difficult case into an intra-party gender war.

Labour and press commentators often talk about the SNP’s almost unnatural unity as if it is centrally enforced. As if there is some dictatorial party secretariat imposing rigid discipline and suppressing debate. Either that, or the SNP is a “cult”, they say, in which star-crossed believers lose their ability to disagree. In truth, it is neither: the SNP is just damned if it will give the hated “mainstream media” stories about splits, so it keeps it in the family.

It wasn’t always so. The SNP used to be notorious for its squabbles and divisions. Mr Salmond was expelled from the party in 1979 for leading a left-wing faction. And the party was deeply divided over devolution in the 1990s. It learned the hard way that unity works. Rather like the Tartan Army, the SNP has found a way to insulate itself emotionally from the disillusion and despondency that afflict most political parties once they starts governing in prose. This is what has prevented the Scottish Government from lapsing into mid-term doldrums and disarray. For its many thousands of members, the SNP has become, not so much a political party, more a way of life.