He is a deeply unpopular figure in Britain, according to opinion polls, and his social media channel has lost users in the country since he took it over in October 2022. Yet when Elon Musk put Britain in his cross hairs on X in recent weeks, pounding the political establishment over a decade-old child sex abuse scandal, he instantly catapulted the issue to the top of the news agenda.

Mr. Musk’s success is rooted in two obvious factors: his mammoth fortune and his alliance with the incoming president of the United States, Donald J. Trump. But it also reflects a British political and media establishment that is divided and deeply in flux, all of which has made Britain easy pickings for an outside influencer with vast resources and a single-minded mission to disrupt.

Britain’s right-leaning newspapers have picked up and amplified Mr. Musk’s call for a new national investigation of young girls who were sexually exploited in several towns in the 2000s, including in Rotherham, where an estimated 1,400 girls were exploited by “grooming gangs” composed largely of British Pakistani men.

The leader of the opposition Conservative Party, Kemi Badenoch, threw her support behind a new national investigation as well, even though the previous Conservative government did not pursue one. A former Tory leader, Boris Johnson, once belittled those inquiries, saying, an “awful lot of money and an awful lot of police time now goes into these historic offenses and all this malarkey.”

The Labour government, which was vaulted into power with a landslide majority in July, has so far rejected Tory calls for another investigation, saying its priority is to implement the recommendations from a previous seven year long national investigation, including tightening requirements to report child abuse and collect better data on cases.