A Labour Party plan to provide government-sponsored broadband service has raised questions about how it would work, and who would pay for it.

No other country provides free government-run broadband service, said Matthew Howett, the founder and principal analyst at Assembly Research, a firm that studies telecommunications.

The prospects of several other companies that compete with Openreach and have pledged billions in investment for their own initiatives would be thrown into doubt after the debut of a free government-run service.

“They all would disappear,” Mr. Howett said. “There is no way consumers are going to be paying them if they can get it for free from the government.”

“Superfast is good enough for today,” Mr. Howett said. “But it’s not going to be good enough for the world we’re entering in the 2020s and 2030s.”