ONE is 46 years old, the other is a pensioner. One can dance Bhangra, the other is a ballroom guy. One is prime minister of Canada, the other is leader of Britain’s Liberal Democrats, who have just 12 MPs. Justin Trudeau and Sir Vince Cable are quite different, but the Lib Dem leader hopes to learn a trick or two from his Canadian counterpart.

Mr Trudeau’s Liberal Party jumped from third place to government in four years, after poaching votes from its rivals on left and right. What can it teach the Lib Dems? Without a long career stretching before him, Sir Vince, 75, has the freedom to shake up his party. One plan under discussion in Lib Dem circles would give non-members a vote on the party’s next leader, a system the Liberals used during Mr Trudeau’s selection. Another idea is to copy the Liberals in doing away with the requirement that the party leader must be an MP. (One non-MP mooted as a possible standard-bearer is Gina Miller, an anti-Brexit campaigner, although both she and the party deny this.) Sir Vince’s team has been in touch with one of Mr Trudeau’s advisers who helped to devise some of the party’s reforms.

The diminished Lib Dems are hardly a “natural governing party”, as Canada’s Liberals are known. But for all their faults, they may still represent the best hope for Britain’s beleaguered moderates. The far-left and the unions have a tight grip on Labour, while the Conservatives’ fate is determined by MPs with a penchant for psychodrama and a small collection of Rotary Club members and tombola-spinners in the home counties. By contrast, the Lib Dems have low barriers to entry, making the party an appealing home for disaffected members of other parties.

Talk of a new political movement has been constant since the Brexit vote. But why bother launching your own party, asks one senior Lib Dem, when you could simply take over one that already exists? After all, the Liberal Democrats have 100,000 members, 98 seats in the House of Lords and, crucially, a toehold in Britain’s ruthless first-past-the-post electoral system, which new parties find all but impossible to crack.

Entryism presents dangers. But for the Lib Dems, scooping up disaffected Blairites from Labour and liberal Cameroons from the Tories is much less risky than it has been for Labour and the Conservatives to ally with hard-leftists and former UKIPpers. A Liberal Democrat party overrun by centrist entryists would look like, well, the Liberal Democrats. “They aren’t Militant, are they?” says one insider, referring to the Trotskyist group that infiltrated Labour in the 1970s and 80s.

Potential defectors may be wary of the Lib Dems. They have baggage. There is a reason why the party’s vote fell from 6.8m in 2010 to 2.4m in 2015. After five years in coalition with the Tories, people no longer liked them. Polls suggest they still don’t: the party limps along at about 10%.

Change could come from the top if MPs from other parties jumped ship. Labour’s anti-Semitism saga flared again this week after it emerged that Jeremy Corbyn, the party’s leader, hosted an event in 2010 at which the actions of the Israeli government were likened to those of the Nazis. But despite disgust among his MPs about his handling of the row, there has been no wave of resignations. Nor has any Tory Remainer MP been persuaded to defect, even as the government’s handling of Brexit has gone from bad to worse.

Instead, Lib Dems are left hoping that an era of political polyamory will replace the 19th-century system of monogamous party politics. New movements and parties should team up with the Lib Dems, believes Tim Farron, a former leader. “They have a lot of generals and naff-all army,” he says. “We are your army.” Such post-party movements are starting to pop up. Cross-party support is growing for a referendum on the Brexit deal, a Lib Dem demand ever since the first referendum. But it would take Labour’s backing to go ahead. Unlike Canada’s Liberals, the Lib Dems are very far from wielding power by themselves. But if some of their ideas end up being enacted anyway, that may be good enough for them.