Vince Cable stepping down as Liberal Democrat leader will endanger the future of the party

There is much evidence that, like it or not, the political centre has shifted towards the left, and towards populist sloganeering from whatever point on the traditional spectrum

There is an old political adage that leaders often quote but rarely act upon when considering when to close their careers. The gist of it is that party leaders, in particular, would rather observers asked, “Why are they going now?” than, “Why are they still around?”

When it comes to Sir Vince Cable, it is perfectly true that no one was particularly asking why he was still leading his party, but it is also the case that no one is asking why he is choosing to go as soon as, in his formulation, Brexit is stopped or resolved. By avoiding questions of either kind, he may be the first to confound the dictum.

He is also gambling with his party’s future in advocating a radically different pattern for party membership (open and free) and, almost alone among national parties, in opening up the party leadership to those outside the House of Commons. The name of Gina Miller is often dropped in this context, although she has ruled it out, but there are prominent businesspeople and others who might like to take on the challenge. There is also some gossip about David Miliband or one of the many Labour moderates taking over. The only people who don’t seem to be spoken of much are the party’s own MPs, and particularly Jo Swinson, the deputy leader, Layla Moran and Sir Ed Davey. You wonder whether Sir Vince was actively looking to snub them.

Perhaps the Liberal Democrats have it in mind to recast their party as a sort of British version of Emmanuel Macron’s En Marche! movement in France. That was in effect a new party of the radical centre, along the lines the Liberal Democrats fancy themselves to be and, in the more distant past, the Social Democratic Party (SDP) marketed itself as when it broke away from Labour in 1981.

It is certainly curious that, at a time when the broad centre of British politics lies neglected by the two main parties moving to more extreme positions, the Liberal Democrats have been unable to capitalise on these trends. They, and their predecessor parties, have done so in the past. Today, however, the party remains becalmed, with double figure polling numbers and Commons representation mostly an aspiration rather than reality.

The reason, however, is quite straightforward. Whereas in other times the public has been prepared to believe, realistically or not, that the Liberals, Liberal Democrats or SDP had a chance of actually winning seats and the balance of power, that seems remote now. The “wasted vote” argument is back, with a vengeance.

The British electoral system has always been brutal towards third parties and insurgencies. The French method of successive ballots for the presidency allowed Mr Macron to create a coalition in opposition to Marine Le Pen’s Front National. There is no such route to power in the UK.

Ask David Owen, David Steel, Caroline Lucas or even Nigel Farage. The success of new parties and “insurgents” is largely confined to moving each of the main parties, and making them more competitive. The SDP gave rise to new Labour; Ukip gave rise to the Brexit referendum, less happily.

Moreover, there is much evidence that, like it or not, the political centre has shifted towards the left, and towards populist sloganeering from whatever point on the traditional spectrum. On issues such as equality, on the power of big business, on nationalisation, the centre is itself moving, though Jeremy Corbyn remains a political outlier. Many disillusioned Labour voters voted Leave, which could be seen as a shift in opinion away from centrist views, and towards an inchoate populism.

The chances are that – for all the visionary thinking, ferment of ideas, and the finance said to be readily available – any new grouping of the centre, wrapped around the Liberal Democrats or not, would suffer from the weaknesses Shirley Williams identified before she herself helped form such a party, the SDP: “No roots, no principles, no philosophy and no values.”

Tony Blair declares that he thinks that it might be “game over” for Labour, and that the health of the party is irrecoverable. With his record in office he deserves respect. However, he knows better than anyone how, in time and with hard work, and electoral punishment, any political party can be brought back from near death – even the Conservatives (as recently as 2015), and the Liberal Democrats (in their breakthrough in 2010). Labour looked equally unsalvageable under Michael Foot in 1983, the general election when Mr Blair entered the Commons. A new centre party has much to commend it in theory, but immense practical obstacles.

“Breaking the mould” of British politics is never easy, and never fast. It took, after all, most of the first half of the 20th century for the Labour Party to displace the Liberals. Even then, Labour splits in the 1930s, 1950s and 1980s helped the Tories maintain a grip on power.

A new party cannot be supported, then, if the consequences are another decade or two of Conservative extremism, to be inflicted on the country on a minority vote. Leaving the EU, as the neo-Thatcherites well realise, is one necessary but not sufficient condition for them to implement hardline neoliberal policies. A split on the centre left is another.