Struggling to find a talking point to take from last week’s Lib Dem conference, much of the media opted to focus on perhaps the ultimate example of what The Independent’s Jon Rentoul would call a QTWAIN – could Vince Cable become the country’s next PM? The BBC’s Question Time even devoted ten minutes to the topic although, to be fair, the Lib Dem leader was one of the panelists.

This unlikely theory – 100/1 with the bookies and bigger on Betfair –  does have some logic to it. We are living through an unprecedented era of political upsets. The fallout from Brexit has some potential to seriously re-align our party system. There is space for a so-called ‘centrist’ party while both Labour and the Conservatives lurch towards their ideological extremes.

I’ve even made precisely that argument before – with regards James Chapman’s mooted ‘Democrats’ party. Stranger things have happened than a brand new party suddenly capturing the mainstream, in times of dramatic political change. Ask Emmanuel Macron.

The fundamental problem for Cable, though, is that his party is anything but new. It’s brand is well-established and, since 2010, that brand has been ruined. Furthermore Cable and his predecessor Tim Farron have shown absolutely no indication of understanding why their reputations were destroyed.

In that respect, they make the same error that most of the political class made regarding the rise of Jeremy Corbyn and Momentum. That led so many to predict Labour would collapse in England just as they had in Scotland. Lest we forget, early in that election campaign 150 was regarded around a par total.

Back then, my first prediction for that election was a bet at 3.5 on Labour beating 177 seats (they got 262). Not because I thought there would be a hung parliament, but because I firmly believe there is a limit to the number of Conservative voters in the UK and they are currently very close to maximising it.

The consensus is now that Theresa May blew the election, yet she got 43.5% of the vote – unimaginable at any election since 1992. Perhaps with a better campaign the Tories would have got 45%, and with it a working majority, but their ceiling is scarcely higher. The fundamental dynamic in UK politics has always been Tory or not. Corbyn’s great achievement was to somehow unite the nots, who are usually split several ways between liberals, greens and nationalists.

He did it by tapping into the mood that had characterised past Lib Dem advances. A genuine agent of change from ‘politics as usual’ – remember Nick Clegg attacking ‘the labservatives’ in 2010? A brand based on idealism, liberal values and grassroots ‘pavement politics’. With living standards falling or static, foreign policies failing and the political class less trusted than ever, that space has been open for over a decade. The Lib Dems vacated it after 2010, and Corbyn has recently made it his own.

Week in, week out, Momentum activists are pouring into marginal seats that was unimaginable during the New Labour years. That used to be the Lib Dems’ preserve. Many Momentum activists, and Corbyn voters, were among the young people that fuelled ‘Cleggmania’. This summer has seen Corbyn playing to big crowds in once Lib Dem seats where Labour were irrelevant less than a decade ago – in Southport and in Cornwall. If there had been a Glastonbury festival before the 2010 election, I’d like to bet the Lib Dems would have topped a poll among that crowd.

In going into coalition with the Tories, Clegg and most Lib Dems totally misread their voters. Their loss of the university vote after betraying them over tuition fees is famous but I’ve always felt other groups were overlooked. This liberal idealist tendency, the anti-war vote picked up due to their opposition to Iraq. Tactical Labour voters in Southern marginals, told for a generation that “Only the Lib Dems can stop the Tories”. Voters who just want to kick the system – many of whom took the ideologically illiterate move towards UKIP afterwards.

Have they sought to recreate that coalition? Not in the least. Cable – before 2010 an arch-critic of austerity – now falls in line with the neoliberal hegemony that simplistically labels any extra spending as ‘unaffordable’, regardless of any longer-term payoff. He was attacking Labour for ‘Venezuelan economics’ a few weeks ago, only to jump immediately on the bandwagon to scrap the public sector pay cap the moment it offered a headline opportunity.

Rather than court the people who supported his party’s opposition to the Iraq war, or build a tactical alliance with Labour, Farron couldn’t wait to attack Corbyn’s foreign policy critique during the election. It reeked of the opportunistic, swing-both-ways tactics that critics have always attacked the Lib Dems for. It is wholly out of touch with this era, when authenticity and principle is so valuable.

In my experience, Lib Dem members are a bit like me. Political nerds really interested in the most detailed areas of the subject. However I’ve never deluded myself that we are in any way representative of society. People didn’t vote Lib Dem because of their commitment to constitutional reform or Euro-enthusiasm. After 2010, they weren’t likely to be aware of the pupil premium, or even who was responsible for their tax cut. Unfair perhaps, but reality.

Now they’re making exactly the same mistake in obsessing about Brexit. Yes it’s a big issue but the most fervent Remainers are a small minority, usually living in their particular bubble within cosmopolitan cities and university towns. In other words, where Labour are completely dominant and where a Lib Dem vote will do nothing to stop the Tories from pursuing whatever version of Brexit they choose.

The wider public – mostly in Leave-voting constituencies – is simply never likely to engage with, let alone support, this Lib Dem strategy. Anti-Brexit is now becoming their entire brand. What happens after 2019, when it seems extremely likely we will leave? Regardless of the fallout and who is to blame – which will inevitably be as hotly disputed as it is now – the public will have moved on to the traditional bread and butter domestic issues like taxes, entitlements, health and education.

These are the issues, incidentally, that Labour’s manifesto very effectively addressed. I feel there’s a tendency amongst metropolitan-based commentators to over-rate Brexit as a reason for their good performance. Being the ‘Softer Brexit’ party surely doesn’t explain them spectacularly defying expectations in strong Leave seats like Hartlepool and Halifax.

As argued recently when advising a bet on Labour, I suspect hostility towards the Tories will grow throughout this parliament.  That leaves few realistic options for ‘liberal centrists’. They either hold their nose and vote for either a left-wing, Corbynite Labour or what will likely be illiberal, nationalistic Conservatives. Or they create something new. As so many said before pretty much every election in living memory apart from 2005 and 2010, the Lib Dems will be seen as a wasted vote.