LONDON, June 10 -- The lobbying came on official paper. The United States government, through its embassy in London, formally asked Britain not to protect its children the way Britain has decided to protect them, warning in a submission to the government's consultation against blunt regulatory instruments and broad social media bans. On Tuesday, Downing Street gave its answer: the crackdown goes ahead.

Keir Starmer is expected to announce a ban on social media for under-16s within days, Bloomberg reported, following the model Australia switched on last December. The prime minister's position hardened after the government's own consultation came back, with roughly nine in ten responding parents backing a ban, a number that converts child ...