LONDON—British Prime Minister Boris Johnson does not need to self-isolate even though a member of his staff on a recent trip to Scotland tested positive for the coronavirus, his Downing Street office said. Johnson visited a police college in Fife on Wednesday and a wind farm off Aberdeenshire on Thursday. Local media reported a member of Johnson’s staff who accompanied him to the police college and travelled with him on a plane tested positive for coronavirus. “The Prime Minister regularly visits communities across the UK and all aspects of visits are carried out in line with COVID guidance,” a Downing Street spokesperson said. “The Prime Minister has not come into close contact with anyone who has tested positive.” Last month Johnson and finance minister Rishi Sunak both self-isolated in line with national guidance, abandoning heavily criticised plans to take part in a pilot scheme that would have allowed them to …