As Britain opens up its pubs, hairdressers, and gyms, optimism is in the air. But the news that a significant cluster of the South African coronavirus variant has been found in south London has cast a cloud over the reopening there. Officials are deploying surge testing in the boroughs of Wandsworth and Lambeth after 44 confirmed and 30 probable cases were identified. Danish Perwez, 33, who works for Lambeth Dry Cleaners & Laundry, has read...