ANOTHER political year begins in Holyrood, and Scottish Labour begins it with another leadership crisis, following the abrupt departure of Kezia Dugdale, their third leader since the independence referendum. Labour should have been looking forward to taking on Ruth Davidson's upstart Scottish Tories in parliament. Instead, anther leadership snafu. Since the first First Minister, Donald Dewar, died suddenly in 2000, Labour has had an almost continuous crisis at the top.

The second First Minister, Henry McLeish, resigned in disgrace over a “muddle not a fiddle” to do with his constituency expenses when he was an MP. His successor, Jack McConnell, had some successes including the smoking ban, but resigned after he ushered the SNP into power in the 2007 election. His successor, Wendy Alexander, resigned in tears a year after that following an obscure donations scandal.

Iain Gray took the reins but ended up galloping into a Subway sandwich shop during the 2011 election, which he lost by a landslide despite having begun the campaign with a 10 per cent lead over the SNP. Johann Lamont then stepped up to the plate, in 2012; and then stepped down again in 2014 accusing London Labour of treating the Scottish Party like a “branch office”. That made her the SNP's pin-up of the year.

The ultra-Unionist, Jim Murphy, took over on a wave of press boosterism after the independence referendum, only to lead Labour to its worst ever defeat in the tsunami election of 2015 when it lost 40 seats. His deputy, Kezia Dugdale, looked like the ideal figure to take Labour into a new era, despite having been in Parliament only three years. She was bright, witty on social media and prepared to be flexible. One of her early acts was to allow the Scottish Labour conference to vote with its instincts and reject Trident – not that this had any impact on the UK party, which remains pro-nuclear. She also tried to outflank the SNP, and atone for years of Blairite orthodoxy, by calling on Nicola Sturgeon to restore the 50p top rate of tax.

She never looked entirely comfortable, however, in the bruising world of Scottish Labour politics. Dugdale's departure has gladdened the heart of every hard-boiled factionalist and misogynist in the Scottish party. She said she was resigning, essentially, for personal reasons, to “get a life”, and pursue her relationship with her new partner, the SNP MSP Jenny Gilruth. This was a slap in the face for the Labour rank and file who'd been spending much of their lives trying to get her elected – with some success. She'd just led the party back from oblivion in the June General Election, gaining six seats from the SNP, when everyone expected Labour to be wiped out. Surely, only the Scottish Labour Party is capable of losing leaders when they’re actually doing well.

The party now has a Hobson's choice between the tainted right-winger, Anas Sarwar, and the untried leftist Richard Leonard of the GMB. This cannot but reopen divisions in the party. Most of the leadership of the Scottish party, like Sarwar, hate everything that Jeremy Corbyn stands for. The left, led by the Neil Findlay of the Campaign for Socialism, (who's not standing), was an embattled minority before the June election. Everyone assumed that Jeremy Corbyn was going to crash out of history by losing by a landslide to Theresa May. Corbyn mania is a very recent phenomenon that has taken, not only Labour, but also the SNP by complete surprise.

Kezia Dugdale wasn't really on either side, left or right, since she was just in the door, politically speaking, and had no firm ideological roots. She went with the Labour mainstream in Westminster, which regarded Corbyn as a serially disloyal, superannuated Trot, but above all a hopeless loser. Hence Dugdale's remarks about him being “incapable of leading Labour to victory”. Few thought any differently back then, even people like the Guardian columnist, Owen Jones, who is now one of Corbyn's biggest fans. Indeed, there was nothing wrong with Kezia Dugdale changing her mind about Corbyn, just like Jones and many others had.

She was undoubtedly hounded by left-wing opponents in the party, but that's par for the course in a party where everyone hounds everyone, eventually. It's not personal. At least she wasn't the target of dirty tricks and damaging leaks to the press, like previous Scottish leaders. No-one cared about her being gay, which if anything is a political advantage in ultra-liberal Holyrood politics. She wasn't particularly good at First Minister's Questions, except when speaking about the rape clause, and she tended to gabble in interviews. But these were things that could be sorted.

No, there really wasn't any excuse for Kezia Dugdale's departure. Perhaps she just lacked a reliable posse of supporters who could bolster her ego. She had supporters in the press, including the Times columnist, Kenny Farquharson, who went as far as to predict that she would be the next First Minister of Scotland. It is a grim reflection on the state of Scottish Labour politics that it has managed to lose a relatively successful leader almost by accident. Labour's brand was already tainted, and an ugly leadership contest, in which the private education of Anas Sarwar's children seems to be a key issue, is not going to help.

Ruth Davidson, the most gifted opportunist in politics, has seen the vacuum on the unionist centre-left and is losing no time trying to fill it. On Friday she made an audacious play for the Labour vote by calling for a mass house-building campaign. This would include thousands of new council homes and, according to her interview on Friday's Good Morning Scotland, seizing land from speculators before it gets planning permission. The irony is that Ruth Davidson is also gay and has had more venom and abuse poured upon her than Kezia Dugdale ever has. Being a female leader of the Conservative Party is not a job for the faint-hearted in a country where "Tory" is still a four-letter word for many. But Ruth Davidson seems to thrive on it. She is like a dynamo on the campaign trail and moves too fast for misogynists, homophobes or ordinary Tory-haters to land any blows.

So what is it about Scottish Labour culture that makes it unable to incubate viable leaders? Is it partly to do with its inability to come to terms with the national question in Scotland? Labour hates the SNP with a loathing that is barely rational, given that they are on the same side on many issues, Brexit only being the most recent. It sometimes seems to turn this loathing inward as it struggles to find a way of dealing with the “Nats”. Kezia Dugdale tried to unroll the old blueprint for federalism, but was disowned by Jeremy Corbyn – not so much because he opposed home rule but because he just doesn't care about constitutional politics.

But they can’t blame Corbyn. Looking back over the past 20 years, it's clear that Scottish Labour's perennial crisis of leadership has been almost entirely of its own making. The Scottish Parliament was Labour's creation and they were the dominant party in Scotland as late as 2010, when Labour won 41 seats in the general election against the SNP's six. The precipitous decline wasn't inevitable. It was largely about a ruinous inability to find and then support a leader of substance who could command the confidence of Scotland. Really, it's as brutally simple as that.