LONDON — The annals of British politics are filled with stories about the government’s iron-fisted, sometimes terrifying control of parliamentary affairs.
One former Labour cabinet secretary, Jack Straw, recalled his first encounter as a young member of Parliament with his party’s enforcer, who stopped him in a corridor and grabbed him between the legs. When he asked the deputy chief whip what he had done wrong, the answer was nothing.
Then the whip added, “But think what I’d do if you crossed me.”
The many tales of British lawmakers once being kept ruthlessly in line stand in stark contrast to the events of the last week, as Prime Minister Theresa May and her lieutenants tried ineffectually to get her party members to support the government’s plan on withdrawing from the European Union, known as Brexit.
Her ally Michael Gove, the environment minister, tried on Tuesday morning to scare some wayward lawmakers straight, using the foreboding terminology from “Game of Thrones” to warn them that “if we don’t vote for this deal tonight, in the words of Jon Snow, winter is coming.”
But that tactic didn’t work, either, and Mrs. May was abandoned by much of her own party on Tuesday night, in a vote that defeated her flagship Brexit deal by a margin of 230 votes, the largest in recent British history.
The Brexit fiasco seems to be forcing a tectonic shift in how Britain is governed, as Parliament flexes its muscles and the prime minister struggles to force through her agenda — a dynamic more characteristic of America’s gridlock-prone system.
The parliamentary rebellion is embodied by John Bercow, the hyperarticulate, pugnacious speaker of the House of Commons, a nonpartisan position.
The son of a used-car salesman from North London, Mr. Bercow entered Parliament in 1997, and with his working-class background, he stood out among the elite Etonians of the Conservative Party.
A longtime advocate on behalf of backbenchers, Mr. Bercow last week scandalized traditionalists by allowing one of these junior lawmakers to put forward for vote an amendment — which passed — that required Mrs. May to come up with a Plan B for Brexit within three working parliamentary days of Tuesday’s vote.
Such permission had not been granted in decades, and many British newspapers were indignant, describing Mr. Bercow the next day as a “sweaty, self-important gnome” and an “egotistical preening popinjay.”
But Mr. Bercow seemed to savor his decision, declaring on Monday, “I will not be pushed around by agents of the executive branch.”
“They can be as rude as they like, they can be as intimidating as they like,” he added. “Unlike some people in important positions, I have been elected, re-elected, re-elected and re-elected as speaker to do the right thing by the House of Commons. That’s what I have done, that’s what I am doing and that’s what I will go on doing.”
On Tuesday night, the lawmakers’ rebellion culminated with Mrs. May’s outsized and far-reaching defeat.
Politics students in Britain are taught the phrase “elective dictatorship,” coined by a former lord chancellor, to describe the executive arm’s dominance over Parliament; that term may have to be retired.
“Constitutional scholars are going to be dining out on this for years,” said Rob Ford, a professor of politics at the University of Manchester. “There are going to be whole Ph.D.s written on January 2019.”
Behind this change lie political shifts that have made it harder for British governments to secure convincing majorities in Parliament, with inconclusive elections and minority governments starting to become the norm.
When Mrs. May called an election in 2017, expecting to win by a big margin, she instead lost the majority she had inherited, leaving her weakened ahead of the generational legislative challenge of negotiating Brexit.
Brexit cuts across traditional voting loyalties, with people switching their allegiances more frequently, which has posed another test for politicians.
“You’ve got a breakdown of the way traditional political parties have worked,” said Bronwen Maddox, the director of the Institute of Government, a London-based policy group. “M.P.s are supposed to follow what their party leader says. Now, they are pulled by the way their constituents will have voted, and by their own beliefs.”
Also, the mystique around the party whips has dissipated, with no more recent stories like the bodily assault recounted by Mr. Straw, who went on to become Prime Minister Tony Blair’s foreign secretary.
“They were thought to use all kinds of dark arts, threatening to blight an M.P.’s political career, but now their tactics have started to look like they’re calling M.P.s in and saying, ‘please,’” Ms. Maddox said. “On an issue like this, when M.P.s are really feeling emboldened to vote their conscience, the party system really isn’t working.”
The shift worries conservatives like Tim Stanley, a historian and journalist, who says Britain’s system presumes that policies promised in party manifestoes will be carried out by the executive. That system confines Parliament’s role to scrutinizing the executive.
Increasing the role of parliamentary backbenchers in shaping policy, Mr. Stanley said, would allow small factions to subvert executive authority, not just on Brexit but on matters like health care and taxation, rendering the British government “effectively rudderless.”
“We have far fewer checks and balances than people realize,” said Mr. Stanley, who writes for The Telegraph newspaper. “It may sound dictatorial, but that’s why our democracy has lasted. That’s the democratic consensus, as it has functioned. That’s why we haven’t had lots of civil wars.”
Mrs. May, in any case, is not likely to forget the lawmakers who sped the way toward her epic loss on Tuesday. After the votes were tallied, they were announced out by her foghorn-voiced adversary, Mr. Bercow.
Orignially published in NYT.