When Britons voted in a referendum to leave the European Union in 2016, Brexit campaigners promised to “take back control” of the country’s frontiers, a pledge that was widely assumed to mean that immigration would fall, but the new figures show net migration is now slightly less than double its pre-Brexit peak.

The cabinet minister responsible for migration, Suella Braverman, is a hawk on the issue, and she has appeared to criticize her government’s policy on the question; last year said she wanted net migration numbers to fall below 100,000 a year.

Her comments have even raised speculation that Ms. Braverman might resign over immigration policy and try to position herself as a potential successor to Mr. Sunak if the Conservatives lose the next general election, expected to take place next year.

Beneath the political tensions lie a striking change in the profile of immigrants since post-Brexit rules came fully into force in January 2021, the date at which E.U. citizens lost the automatic right to work in Britain and faced the same visa restrictions as other nationalities.

Since then, the number of Eastern Europeans entering Britain has dwindled to a trickle while British employers have increasingly recruited from India, Nigeria, Pakistan and the Philippines, as well as other non-European nations.