Witty repartee still features in Parliament. But does it persuade anymore?

Night had fallen when Sarah Jones rose from the green-upholstered bench in the House of Commons. Ms. Jones, the member of Parliament for Croydon, noted the late hour and what Oliver Cromwell had said in 1653 on dissolving the so-called Long Parliament.

“You have sat here too long for any good you are doing,” she quoted.

A baritone chuckle erupted from the opposite bench.

Ms. Jones smiled. “Nevertheless we carry on,” she said.

She then used her allotted seven minutes on the third day of the Brexit debate to lambast the failures of the Brexit agreement and the failure of government to properly inform Parliament during the negotiations. She accused ministers of using speeches to the House “as a kind of parliamentary CalPol [pain reliever] to keep the babies quiet.”

“Oh, I like that,” said a colleague on the row in front, turning around to Jones.

Witty repartee, rousing oratory, and cut-and-thrust rhetoric are considered the essence of British parliamentary debate. The dry, dutiful speeches and written testimony of Congress has no place on the floor of Parliament, where MPs carry bundles of paper mostly to wave at their rivals. For centuries, the demands of oral debate has sharpened the wits of lawmakers and leaders and tested their mettle in the braying bullpen that Parliament sometimes resembles.

But today the verbal jousting often ends up more as pantomime than persuasion. Rarely does an issue come to a vote without MPs taking positions before all the arguments are heard. Even on a vote as critical as Brexit, the most consequential in a half-century, the call of the orator is muted; what is billed as a clash of titans seeking a red-hot truth becomes a routine roll call.

Some blame the dug-in battle lines of Brexit.

“I doubt anyone has changed their mind, not just in the Commons, but across the country,” says Michael Deacon, the Daily Telegraph’s parliamentary sketch writer, a venerable, semi-satirical role once inhabited by Charles Dickens. “If anything, people on both sides are becoming more fanatical, more furiously certain.”

Others look back to golden eras of parliamentary speechifying, the patriotic oratory of Winston Churchill, who told the House in 1940 he had nothing to offer but “blood, toil, tears, and sweat” to a national-unity government. Or the tireless moralizing of William Wilberforce, who took 18 years to persuade Parliament to end slavery in the British Empire in 1833.

By comparison, Britain’s modern politicians seem too bloodless or meek to rouse their peers. Parliament has also become less central to the nation’s political conversation, as debates over matters of state have moved out of the chambers and tearooms of Westminster and into the studios of a 24-hour news media. Newspapers no longer publish lengthy reports on the previous day’s parliamentary proceedings. When Prime Minister Theresa May sought to push back at the critics of her beleaguered Brexit deal on Thursday, she subjected herself to a relentless 23-minute grilling on a BBC radio show.

MPs must engage more directly and more intensely with their constituents than their postwar predecessors who enjoyed a slower pace of news, says Ruth Fox, head of research at the Hansard Society, an independent political research institute in London. So when they rise to explain their stance in the Brexit debate there are no bombshells. “They probably announced it already on Twitter or Facebook,” she says.

Still, MPs have to think on their feet and speak extemporaneously, particularly if they sit in government. And to do so in a way that is polite, droll, and perhaps a little supercilious.

‘Brexecuted’ politics

One aspect of parliamentary debate is that all speakers, including the prime minister, must take interruptions, though just as a comedian handles hecklers, it can be turned to advantage.

On Thursday, Chancellor Philip Hammond was making fitful progress in extolling the economic benefits of May’s Brexit agreement. A Labour MP, Steve McCabe, insisted on making a point.

“Will the chancellor give way?” he asked, rising to his feet.

“In the absence of any better offers, I will give way to the honorable gentleman,” Mr. Hammond replied, as he sat down.

“The chancellor is as kind as he is funny,” responded Mr. McCabe.

A different knock against MPs is that their gladiatorial debates are an elitist parlor game that are at odds with the ways of modern Britain. Viewers at home see “a pantomime farce” in the chamber and ask why anyone can get away with that kind of behavior at work, says Ms. Fox.

Speaker John Bercow, a Conservative MP who is obliged to be a neutral referee and rule-setter, seems to spend half his time calling MPs to order and scolding them for “sedentary chundering,” or yelling from their seats.

Yet this charge of elitism may be misplaced. Some of the great parliamentary debaters of the 20th century emerged not from the fancy prep schools and universities of the upper classes but the union halls and Methodist meetings that favored the orator and the tactician alike.

And the power of parliamentary persuasion is not entirely lost. In 2015, Hilary Benn, Labour’s shadow foreign secretary, defied his own leadership to make a passionate speech in favor of military action in Syria that is credited with moving war-weary MPs to back the government’s motion.

Perhaps the repetitive rows over Brexit in its excruciating details have become an impediment to rhetorical reasoning. “At no point in parliamentary history, except during world wars, can debate have been so suffocatingly narrow,” says Mr. Deacon. “Normal politics has been Brexecuted.”

There was a hint of weariness on Thursday when John McDonnell, Labour’s shadow chancellor, rose to deliver his riposte to Hammond’s testimony. As he complained that the deal was not bringing the country together, David Morris, a Conservative MP rose from the opposite bench.

“I am listening with intent to what the right honorable gentleman is saying, which is very measured,” he told the House. “Speaking apolitically and being measured myself, I ask whether he would please consider voting for this deal, so that we can all move on with our lives.”