A week after the EU referendum, an ally of George Osborne approached Liberal Democrat leader Tim Farron and suggested the creation of a new centrist party called “the Democrats” (the then chancellor had already pitched the idea to Labour MPs). For nearly two years, conversations such as this one have been taking place among senior politicians. Peter Mandelson, according to Labour figures, is one of those "serious" about creating a new party. This week's Economist endorses the Liberal Democrats as a "down payment" on such a project.

It was the election of Jeremy Corbyn as Labour leader that first triggered the discussion. Only a fraction of MPs shared Corbyn's politics and most regarded him as unelectable (and still do). In 1981 the Social Democratic Party was formed as Labour moved leftwards. Many of Corbyn's opponents argued that their plight was far worse; never before had the left held the leadership (Michael Foot was no Bennite).

The EU Remain campaign, during which Conservative, Labour and Liberal Democrat politicians worked closely, and Leave's subsequent victory, intensified the conversation. Blairites, Cameroons and Cleggites (economically liberal, socially liberal and internationalist) all spoke of feeling "politically homeless". The decision by two reluctant Remainers - Theresa May and Corbyn - to back Brexit, it was argued, paved the way for a new movement of "the 48 per cent". Corbyn and May's shared rejection of liberalism, meanwhile, has created a pool of willing business donors.

Though there are vast differences between the British and French political systems, Emmanuel Macron's triumph further energised this tendency. Despite being founded just 14 months ago, En Marche! is on course to win a majority of National Assembly seats. The traditional big two - Les Républicains and the Parti Socialiste - have been left in the dust.

But if the French election has given centrists cause for hope, the British election has not. Many of those backing a new party anticipated a Labour collapse and a Liberal Democrat surge. Yet by any measure, Jeremy Corbyn has outperformed expectations while Tim Farron has underperformed them. That the former has done so is in part due to an interventionist manifesto of the kind rejected by centrists.

Even if the Conservatives still achieve a comfortable majority of 50-plus, Labour will remain a viable opposition. The failure of the Lib Dems' anti-Brexit stance to appeal reflects the non-existence of "the 48 per cent". As I wrote a month ago, the crucial figure is the "69 per cent" - the number who believe the government has a duty to leave the EU (more than a third of whom voted Remain). Even for the 20-25 per cent who wish to overturn the result, Brexit is far from only the issue on the ballot.

These obstacles have been added to pre-existing ones: the tribalism and loyalty of most Labour and Conservative candidates, the UK's adversarial model and first-past-the-post (a life support machine for the two-party system). There is a paucity of senior politicians available to lead a new party. Mandelson, Tony Blair and Nick Clegg (all of whom have flirted with the idea) long passed their political peak. Labour has no figures of the stature of the Gang of Four (two of whom, Roy Jenkins and David Owen, had held great offices of state): its medium-sized beasts far outnumber its big ones.

Rather than founding a new party, Britain's "homeless" liberals need to colonise its old ones. In this respect, ironically, they have much to learn from the reviled Corbyn. As left-wingers abandoned Labour during the Blair years, the Islington backbencher kept the faith. By using the one-member-one-vote system to recruit thousands of new members, Corbyn and his allies achieved an internal revolution. If they ever want to regain their former standing, centrists need to do the same.