“It’s like the country is turning upside down,” Mr. Anderson said last year when he was canvassing voters. “As bizarre as it seems, Boris and Donald Trump connect with working-class voters. People like plain English.”
Mr. Anderson, on his Facebook page, said he lost his sense of taste on Friday, a day after he and four other lawmakers attended a breakfast meeting with Mr. Johnson. His positive test was returned on Sunday, which prompted the National Health Service’s contact tracers to get in touch with Mr. Johnson.
During his self-isolation Mr. Johnson plans to work from his apartment, which is above 11 Downing Street. He will also have access to his office at number 10 next door without walking through parts of the building where others work. Unlike his previous period in quarantine, Mr. Johnson will not have to live apart from his family.
Mr. Johnson will maintain a full schedule of events, conducted remotely, and hopes to use a video link to take part in Prime Minister’s Questions, his weekly grilling by the leader of the opposition in the House of Commons.
Although this is yet another critical week for the trade negotiations, analysts expect a meeting of European Union leaders on Thursday to be another in a succession of missed deadlines. Unlike many such negotiations, which come down to obscure details, this one has reached a politically charged endgame, with disputes over fishing rights, state aid rules, and guarantees of fair-market competition.
“It’s not insoluble, but we are in a holding pattern,” said David Henig, director of the U.K. Trade Policy Project at the European Center for International Political Economy, a research institute. “The political issues haven’t been resolved, and nothing is being done differently that makes one think that they can.”