COUNTERFACTUAL pol­itics can be a fun game to play. What would British politics look like now, if Nick Clegg hadn’t decided to take a long walk with David Cameron in the rose garden and embrace a civil partnership with the Tories in 2010?

Would the political damage still have been as extensive if he hadn’t ratted quite so extravagantly on their tuition fees pledge to the students? Or, having ­chosen to ­embrace austerity, and champion it, were the ­Liberal Democrats always ­going to be left drifting around the country like Lady Macbeth, ghosts of their ­former selves, ­trying to scrub away the political stains, ­consoling ­themselves with all the ­knighthoods, ­peerages and gongs the ­party’s ­“grandees” are past masters at ­accumulating for ­themselves?

Tweak the political timeline another way. Imagine Clegg decided to keep hold of the balance of power over a minority Tory ­government in Westminster rather than joining the Conservatives 10 years ago. Would this stance have lost the LibDems the 49 seats it cost them in 2016?

If not, would the Tories have achieved the single party majority which forced ­David Cameron to set in train the referendum on Britain’s EU membership? If not, would the UK still be a member of the European Union now?

READ MORE: Labour and LibDems vow to collaborate in attempt to win over SNP and Tory voters

You don’t need to squint too hard to pick out what looks like a straight ­casual line between the Liberal Democrats’ ­decision to join the UK Government in 2010, the collapse in their own support as a ­consequence, and the creation of a political context where first the European ­referendum, then Brexit, then Tory domination of English politics became possible. These are the kinds of questions which haunt political careers and political legacies – or which ought to haunt them.

There are other ironies, if you go ­hunting for them. If the Liberal Democrats hadn’t colluded in austerity, would Boris ­Johnson’s now be in the position to make political capital by fixing problems ­created by the Conservative Party, supposedly ­“levelling up” those parts of the UK he and his colleagues spent decades of government levelling down?

Think about the Scottish context too. In 2007, when the SNP emerged with no ­majority but a single-seat advantage over Scottish Labour, the Liberal Democrats ­decided to pull the plug on their long-term coalition partner, ushering in the first ­minority Nationalist ­administration. Did they fully appreciate they were ­exiling ­Labour – and themselves – from the ­governing business for the foreseeable ­future? On Scottish independence, did they realise they were releasing the genie from the lamp?

Punished by the electorate for its ­involvement in the coalition, the collapse of the Liberal Democrats also cleared the way for the SNP’s recent ­domination of Holyrood. From the 17 seats they held in the early days of devolution, the party is now barely a delegation, not even a ­technical group, banished for the first time from Holyrood’s corporate body, denied a routine slot to question the FM. The constitutional outlook seems to have altered too.

Since 2014, save for occasional and half-hearted invocations of “full federalism sometime,” the party has fully ­embroiled itself in the ugly Dutch auction between Scottish Labour and the Tories, as the three unfairly accuse one another of ­being slouches and sell-outs on the ­Union. Today, Scottish Liberal ­Democrat politicians pride themselves on being ­opposed to Scots exercising their right to self-determination as much as any one nation ­British nationalist. Any sense of a distinctive constitutional agenda has evaporated. How this can be construed as liberal, or democratic, is a question for the philosophers.

IF you were scrabbling around for someone to blame for this electoral decline and these decaying principles, a party leader who has been in post for a decade might seem a good place to start.

Having taken over in 2011, Willie ­Rennie announced last week he was ­vacating the party leadership. I know when people ­demit office, you’re ­supposed to write fondly of their better qualities and not dwell on all the things they didn’t achieve during their tenure. But it warrants some comment, I think, that the Liberal Democrats seem so ­intensely relaxed about a political legacy which is characterised by political ­failure and the betrayal of what even their ­opponents would have ­regarded as basic Liberal Democratic ­values.

We’re supposed to think of Willie ­Rennie as some kind of good-hearted Victorian schoolboy with a gap-toothed grin and a face like a polished crab-apple: Just William. I have every confidence that Rennie’s insatiable pursuit of photoshoots will furnish the picture desk with a suitable snap to illustrate this article, but most politicians aspire to achieve more in their careers than being Shadow Minister for Soft Play and paramount lord of the bouncy castle.

“From banging the drum on mental health and education to those amazing photo-ops, Willie Rennie has been a fantastic leader, he is the best of us,” said Sir Ed Davey. For those of you who may have understandably forgotten who he is, Davey is currently the party’s UK ­leader, another body ennobled for coalition ­services rendered.

In another tribute last week, the author painted a picture of Rennie as a leader who played a big-hearted political game with a bad hand. “When he took over in 2011, he inherited a party that had been given the hoofing of its life in the Scottish Parliament elections, reduced from 16 MSPs to just five.”

But of course, that wasn’t the hoofing of the party’s life. The party was dealt that hoofing just a few months back, and from “just five” MSPs, Rennie has led them to “just four.” Struggling on with four MSPs actually flatters their electoral performance. Having lost their ­deposits in 50 seats, the LibDems now only hold the two micro-constituencies in the northern isles, and maintain their grip on North East Fife and Edinburgh Western through rampant tactical voting.

Orkney seems solid, but the situation in Shetland looks shooglier and shooglier. And in the rest of the country? Frankly, they’re nowhere. In May, they lost their sole regional seat in Holyrood, as the seat vacated by Mike Rumbles in the North East turned Green. They don’t have a ­single regional representative to their name.

During the directionless drift of the long decade of Rennie’s leadership of the party, the party made only losses and no gains. If it had any kind of strategy to transcend constitutional divisions, and to track a unique course through the challenges of independence and Brexit, I struggle to see it.

READ MORE: Wee Ginger Dug: Labour and LibDems have no hope of ending English Tory rule

CARON Lindsay suggests that Rennie “showed what he could do with a bright and optimistic campaign which include him launching the manifesto while running down a soft-play volcano and being interviewed on a slide”.

If Rennie showed anything, it is that you can brightly and optimistically lose seats, brightly and optimistically ­preserving yourself in fourth-party status, brightly and optimistically going nowehere. It is ­almost as if voters are looking for ­something more substantive from their politics than a middle aged man hopping incongrously around Glasgow in a wizard costume or practising aikido against an irate sheep. Fancy that.

Rennie leaves his party, on a simple ­numerical reckoning, worse than he found it in 2011. He isn’t the sole author of his party’s misfortunes, certainly, but it is testament to the Liberal Democrats’ recreational attitude to politics that this legacy of political failure is the subject of warm personal tributes and no reflection on the cul de sac Rennie and his clown car have reversed the party into.

The Scottish Liberal Democrats are ­dying, and dying in part because it is now almost impossible to identify what serious ideas they are for.