The remarkable rebirth of the Lib Dems will demand some tough choices – and sooner than you might think

Editorial: Jo Swinson is flying, but she needs to widen her party’s policy offer beyond Brexit and make sure the stance on working with Labour is clear. Otherwise she will see her party dragged down

The Lib Dem leader needs to make sure this isn’t another false dawn (PA)

They’re going to need a bigger minibus.

The defection, or re-defection, of Luciana Berger from Labour to the Independent Group/Change UK and, now, to the Liberal Democrats brings the party’s Commons strength up to 16. It’s still quite a come down from the high water mark of 63, achieved under Charles Kennedy’s leadership, but remarkable progress all the same.

For the first time in a decade, the Liberal Democrats have some solid cause to feel optimistic. With excellent showings in by-elections and the European contests, and the high-profile defection of Phillip Lee from the Tories (theatrically interrupting Boris Johnson’s Commons statement to the G7 summit), they seem to be on a roll.

In many ways, they have the present disarray in the Conservative and Labour parties to thank for their success. The Liberal Democrats’ clear “Stop Brexit” stance has helped detoxify the brand and give them a simple, clear message to offer to the electorate. Having been nursed back from near extinction after the end of the coalition by Tim Farron and Vince Cable, Jo Swinson has injected a good deal of energy and enthusiasm, and some shrewdness, into the leadership.

The party also seems to be an unwitting beneficiary, too, of the polarisation of politics, and its slow conversion from class-based arguments into a sort of culture war. Labour and, to a lesser extent, the Conservatives have the problem of trying to retain their Leave and Remain supporters, both in parliament, in the wider party and among their voting supporters.

However, like Nigel Farage’s Brexit Party at the other end of the spectrum, Jo Swinson’s Lib Dems have no such trouble. The political centre ground and the traditional “bell curve” profile of voters crowded in the moderate middle has given way to a different “twin peaks” pattern, with many voters polarised and gathering around the extremes.

After almost four years of argument about Brexit, we can see the broad contours: better-off, university-educated middle class voters in bigger cities and in London and Scotland in particular tend to favour Remain and pro-Remain parties. Less affluent voters in towns in decline tend to back Leave. Attitudes towards things like migration or LGBT+ rights, more than traditional economic concerns, are becoming the new fault lines.

In this new topography the Liberal Democrats would be well placed to supplant Labour as the natural home of the progressively pro-Europe minded, and in particular those unconvinced by Labour’s statist tendencies, passion for nationalisation and aggressive redistributionist policies. Some will also have been put off by the sustained talk of antisemitism around the party.

Only the sheer size of the Labour machine, its established position, funding and the first-past-the-post voting system offers Labour some defences against the secular trends running hard against it.

It is far too early to predict the strange death of the British Labour Party in the 2020s, in the same way as the old Liberal Party faded away in the 1920s. After all, Mr Corbyn scored the best swing to his party since 1945 as recently as the 2017 general election, and he remains, by a long way, the leader of the largest opposition party.

And yet the Lib Dems are catching up, and Labour tacticians and MPs would do well to shed any complacency about the realignment taking place on the centre left. In an election campaign, with the broadcasters obliged to give the Liberal Democrats a larger share of airtime, and with, prospectively, some interest in their new, young, woman leader, they might be expected to add to their current support at 19 per cent or so of the electorate. If so, then the Lib Dems might soon edge close to Labour’s share of around 25 per cent, albeit that is not saying much.

For the outstanding feature of the British polling scene today is this pitifully meagre Labour strength, measured by historical standards, and confirmed in various recent real-world elections. As in 2017, Mr Corbyn and his frontbench team – which contains some bright talents – might ignite their campaign, if and when it gets going.

On the other hand, as the saying goes, past performance is not necessarily a guide to future results. Two years ago Mr Corbyn was up against a dismally poor performer in Theresa May, and he benefitted from his “creative ambiguity” on the EU. Neither of those conditions looks likely to apply in 2019 or 2020. Labour, in fact, still hasn’t got a coherent message on what it would do in government about Brexit.

Ms Swinson will also need to prepare the answer to the question she, like her predecessors, will be asked incessantly: will you support Labour in a hung parliament, and under what terms?

Thus far, as in the talks about the elusive “government of national unity”, she has been relatively hostile to Jeremy Corbyn, but if he does end up as prime minister-designate in a hung parliament, she will need to find a way of accommodating him, just as he will have to trim the more extreme sections of his party’s manifesto.

Apart from a possible targeting of her East Dunbartonshire seat by the SNP, the bigger, longer-term problem for Ms Swinson is, perversely, the decline of Brexit as a major issue. Difficult though that may be to envisage now, were there to be a deal, or even under no deal, many of the Remain arguments would simply cease to be relevant (though still valid), if the UK has formally left the EU. For reasons of high principle as well as base electoral politics, Ms Swinson has an interest in keeping the UK in the EU, and keeping her party in business.

For now she is doing well, but she obviously needs to widen her party’s policy “offer” beyond Brexit, and make sure the stance on working with Labour is clear. Otherwise she will see her party dragged down by the unpopularity (relatively speaking) of Mr Corbyn, for Lib Dem support is probably not that deeply rooted. Ms Swinson’s predecessors have witnessed many a false dawn. Nick Clegg might remind her of the old Kipling line about success and failure both being imposters.