Darren Major · CBC News

· Posted: Jun 28, 2026 4:00 AM EDT | Last Updated: 2 hours ago

Despite having nearly identical parliamentary systems, Canada has avoided the kind of prime ministerial parade that has befallen the U.K. in the past decade.

Political watchers point to the Brexit vote as the key moment that led to half a dozen leaders occupying 10 Downing Street in the 10 years since — but there are underlying factors that make it easier for U.K. MPs to ditch a leader than their Canadian counterparts.

"I think it's more difficult to govern the country now and that there's a lot of unrest about this decision," Lori Turnbull, a political science professor at Dalhousie University, said of the U.K.'s decision to walk away from the European Union.

"As a result, it's harder for any of the people who are prime minister to stick it out."

At least two of the six recent resignations were a direct result of the Brexit decision. Conservative David Cameron was the first to go in the wake of the 2016 referendum, citing his personal opposition to leaving the EU as his main reason for stepping aside.

Theresa May, Cameron's successor, was later forced out after failing to get her own party to agree on the precise terms of the Brexit deal.

WATCH | Why Starmer had to resign:

May was followed up by Boris Johnson, who managed to push Brexit through but was undone by a series of scandals during the COVID-19 pandemic, which made way for the historically brief tenure of Liz Truss. Rishi Sunak replaced Truss but was unable to turn the Conservatives' tanking popularity around.

Andrew MacDougall — who was former Canadian prime minister Stephen Harper's director of communications and now a partner with Trafalgar Strategy in London — said Keir Starmer, who resigned as prime minister last week, lacked a credible plan when his Labour Party unseated Sunak in 2024.

"[Starmer] won because he was not a Tory," MacDougall said.

"It wasn't that he presented some grand vision for everything and a plan to get there. He was caught on the hoof by the early election call, didn't do the planning, ran into Number 10 Downing without a plan [and] got creamed."

While Brexit may have been a catalyzing moment, MacDougall says global events before and after the 2016 referendum — including the Iraq war, the 2008 financial crisis, COVID-19 and the war in Ukraine — have helped erode public trust in political institutions.

Those events paired with "a disintegrating public sphere" are making governing and politics increasingly "impracticable and impossible to do," MacDougall said.

Canada hasn't been immune to eroding trust in institutions and, beyond Brexit, has also experienced the global events rocking this century.

Different culture, different mechanisms

But both Turnbull and MacDougall point out that the U.K. has a different political culture and more effective mechanisms that have allowed parties to oust their leaders.

The U.K. Labour and Conservative parties both have internal tools that allow caucus to openly challenge their leaders at any point as long as they have enough support. In some cases, as it was with Starmer, the leaders leave before an internal challenge is launched. But that is usually because the writing is on the wall.

In Canada, both the Liberals and Conservatives have a leadership review mechanism built into their charters but it is only activated if the party loses a general election.

The House of Commons also adopted the Reform Act in 2015, which allows MPs to force a leadership vote if they have enough support from their caucus colleagues. But that act has only been used once, in the case of former Conservative leader Erin O'Toole.

Erin O'Toole is the only leader to be ousted via the Reform Act since it was adopted in 2015. (Sean Kilpatrick/The Canadian Press)

The Liberals have never adopted the provisions of the Reform Act, which is why they couldn't use it to force out Justin Trudeau as his popularity waned. Trudeau eventually stepped down, but that was a year after one of his MPs openly called for a leadership vote and others put up an internal push to make him leave.

It is also far more acceptable, and even expected, for backbenchers to challenge their party leaders in the U.K.

"In Britain you have a much more robust political culture that includes challenge from within the party. It is not unusual for backbench rebellions to happen in significant numbers on all manner of policy," MacDougall said.

MacDougall contrasts that with how one backbench MP voting against their party can create headlines in Canada.

• Brexit, 10 years later: What a regret-fuelled British town can teach Canada about referendums

Turnbull argued that it is also more difficult for leaders to manage caucus in the U.K. just because of the sheer size of the British Parliament.

There are 650 seats in the U.K.'s House of Commons. The Labour Party's 403-member caucus is larger than the entire Canadian House of Commons.

In Canada, a leader can use the promise of promotion or demotion in the party ranks to manage a smaller caucus. But U.K. leaders don't necessarily have those options, Turnbull said.

"There's too many people. You can't put everybody in a cabinet, you can't give everybody a diplomatic post. You don't even know them all," she said.

Andy Burnham, widely seen as the successor to Starmer, poses for a photo with colleagues from the Labour Party in Westminster Hall in London. (Yui Mok/The Associated Press)

Additionally, the U.K. party brands tend to supersede a leader's brand whereas in Canada, a leader can put their personal stamp on the party, Turnbull said. She pointed to the differences between the Trudeau-era Liberals and Prime Minister Mark Carney's shift toward the centre.

"To be a Tory in the U.K., to be a Labour member in the U.K., those are deep, deep traditions that I have never seen anyone, any leader, however strong, develop a kind of brand that would transcend that of the party," she said.

MacDougall argued that parties in the U.K. are also becoming increasingly fractured into smaller subgroups that can make it more difficult for leaders to manage, particularly as the information system becomes more fragmented.

He said that as Canada's information system also becomes more fractured, the country could see similar trends of fleeting popularity for its leaders.

"Canada's just a bit behind the curve. I don't think Canada's immune," MacDougall said.