Amid the mass resignations, crying jags, threats of physical violence and assorted other melodrama around the British Labour Party's spectacular meltdown following the Brexit vote, there is one piece of context that should give pause to Canadian partisans of any stripe watching gape-mouthed from afar.

The crisis in which Labour found itself last week, with Jeremy Corbyn refusing to leave its helm despite being abandoned by so many of his party's 229 MPs that he could not even form a full shadow cabinet, is its reward for adopting our own parties' method of choosing their leaders – and a case study in how that system can go horribly wrong.

Until recently, Labour chose its leaders through a complex process in which the party's caucus, affiliated unions and general membership each held one-third of the vote. Only last year, touting the need to be more transparent and participatory, did it become the first of Britain's two leading parties to hold a straightforward vote in which all registered supporters' votes count equally.

Story continues below advertisement

Canada has enough experience with variations of "one member, one vote" – and leadership conventions to which general members elect delegates to vote for their candidate of choice – that most people who work in politics here know well what this approach means. Far from simply leaving the decision to the party's established grassroots, it turns the campaigns into organizational efforts revolving largely around signing up new members.

When something becomes par for the course, it can be easy to get complacent about its nightmare scenario. What happens if voters who may have limited attachment to the party stick it with a leader so at odds with its values and norms, so unable to work co-operatively with the caucus and party apparatus, that the party almost immediately plunges into an existential crisis?

Courtesy of Labour, we have a pretty good answer to that, along with a sort of what-not-to-do guide.

First, a demoralized party launched a campaign with a lacklustre field of mainstream candidates and one very underestimated anti-establishment option, in the form of Mr. Corbyn – a doctrinaire socialist MP who entered with little serious thought of winning. Party higher-ups appeared not to understand what sort of contest their new rules, which included making it much cheaper and easier to join the party than previously, would make for.

They were too far inside the bubble of Parliament or party headquarters to promptly notice the traction Mr. Corbyn was getting, largely through social media, with the sorts of left-wing voters ostracized from Labour since at least the Tony Blair era; they were also caught off guard when the momentum swept up some of the party's existing membership. Too late, they reportedly launched futile efforts to stop him – such as attempts to disqualify his sign-ups – that only strengthened the outsiders' resolve.

Then, after winning with almost 60-per-cent support, Mr. Corbyn bucked usual expectations of new leaders that would have been especially useful in this case. He proved disinterested in outreach to bring skeptical caucus mates on board, reportedly avoided the party's headquarters almost entirely, declined to moderate his policy positions to reflect the party's broader character and was adversarial with even relatively sympathetic journalists. By most accounts, he seems to have continued to act very much as an outsider, while some of the activists who supported him set about making life miserable for the more centrist Labour MPs.

If matters had not come to a head post-Brexit – Mr. Corbyn, blamed for showing little interest in advocating for his party's Remain position, clinging to the leadership over the frantic protestations of almost his entire caucus and much of his own staff – something else surely would have done it.

Story continues below advertisement

This exact chain of events, obviously, will not be replicated here, because the political culture and personalities are different. But given current patterns of political participation and mobilization, our parties probably shouldn't take too much comfort from that.

Over several decades, those inclined to engage civically have increasingly chosen to do so outside the party system. Populist waves can come seemingly out of nowhere to make activists of people who may not even have been regular voters previously. Social media outreach, fused with old-school person-to-person contact, can mobilize them in a hurry. A party at a vulnerable moment might never know what hit it.

Notwithstanding that they are currently in the midst of their own post-Brexit soap opera, Britain's Conservatives offer one potential way of avoiding such conundrums. To choose David Cameron's replacement, MPs will narrow the field to two candidates, who will then compete for the affections of the party's membership – a way of giving broader supporters choice, but not control.

If that's too elitist for Canadians, or the House of Cards-style gamesmanship among Britain's Tory MPs is interpreted as a different cautionary tale, parties can try to make leadership votes a little more exclusive through tinkering. Before launching its current leadership contest, for instance, the Conservative Party of Canada ended cash payments for memberships – a way of making it tougher for candidates' campaigns to hand in giant stacks of new membership forms at once.

Or they can go in the other direction. Under Justin Trudeau's leadership, the federal Liberals recently dropped membership fees altogether in favour of allowing anyone to quickly register as a supporter. It's largely an attempt to boost fundraising and volunteerism, but the long-term gamble is it will allow their party to fashion itself a "movement," as Mr. Trudeau calls it, rather than getting overtaken by one.

What parties cannot do is blithely assume they can have it both ways – opening themselves up during leadership contests, then returning to being the same cozy closed shops they were beforehand. There are systems, such as the one choosing Donald Trump as a presidential nominee, in which the face of the party can be at some distance from its day-to-day operations. The Westminster model, as Labour has ably demonstrated, is not one of them.