LONDON — Amateur lip readers pored over the video clip almost as soon as the British Labour leader, Jeremy Corbyn, shook his head and muttered a few words in disgust.
Had he really called Prime Minister Theresa May a “stupid woman” in the House of Commons? Yes, they agreed, it appeared he had.
The clip quickly bounced around Twitter and onto elected leaders’ phones in Parliament, where members were once again debating Mrs. May’s draft deal for leaving the European Union.
Suddenly, Mrs. May’s Conservative Party, which for months has been torn apart by disagreements over the prime minister’s Brexit plan, was united behind a common cause: forcing Mr. Corbyn to say he was sorry.
“Would it not be appropriate,” asked one member, Patrick McLoughlin, “for him to come back in the chamber and apologize?”
The Conservative side of the chamber roared: “Hear, hear!” and “Bring him back!”
The controversy was set off when Mrs. May was ripping into Mr. Corbyn and his Labour party for their indecision over forcing a largely symbolic vote of no confidence in the prime minister this week.
“They said they’d put down a vote of no confidence, then they said they wouldn’t, then they said they would, then they did but it wasn’t effective,” Mrs. May said.
The camera cut to Mr. Corbyn. Seated across from the prime minister, he could be seen enunciating “stupid” and then what appeared to be “woman,” though the second word was less clear.
The Labour party later said Mr. Corbyn had actually leveled a gender-neutral insult — “stupid people” — though it was not clear who he would have been referring to. He eventually stepped out of the House of Commons.
As the clip made its way around Parliament, Conservative members demanded that the speaker of the house, John Bercow, reprimand Mr. Corbyn. Mr. Bercow tried to step out of the line of fire.
“I cannot be expected to pronounce upon that which I did not see,” he said, “and which was not witnessed by my advisers.”
That set Conservative members into an uproar.
Andrea Leadsom, the leader of the House of Commons, accused Mr. Bercow himself of once having called her a stupid woman, and asked the speaker why he had not apologized.
Mrs. May responded in measured tones.
“I think that everybody in this house, particularly in this 100th anniversary of women getting the vote, should be aiming to encourage women to come into this chamber,” she said, “and should therefore use appropriate language in this chamber when they are referring to female members.”