Britain lifted many of its coronavirus lockdown restrictions Monday as infection rates fall to their lowest levels since August. Pubs, restaurants, theaters, casinos and art galleries opened their doors to allow customers inside for the first time this year. Many families are now able to meet indoors for the first time in months as the new rules allow gatherings of up to six people inside private homes.  The government credits its rapid vaccination program for allowing the easing of lockdown measures. More than 36 million people — well over half the population — have been given a first dose of one of the approved vaccines as of Monday, and more 20 million have received both doses. The government, however, has warned that the rapid spread of a new mutation of the virus first seen in India could disrupt plans to end all lockdown restrictions on June 21. Among the first to take advantage of the relaxed rules were Britons heading off on vacation to Portugal, one of a dozen countries given "green” status by the government due to low infection numbers and high vaccination rates. Matthew Bolden arrived at Lisbon airport Monday from London. “It is fantastic. The feeling is unbelievable. We’ve got the sun, we got the people, the beaches, the bars. Can't wait,” Bolden said.  People look at Luz beach on the first day that Britons are allowed to enter Portugal without needing to quarantine, as COVID-19 restrictions continue to ease, in Lagos, Portugal, May 17, 2021.Travelers from countries given “amber” status, including most of Europe and the United States, still face mandatory quarantine in the place they are staying for up to 10 days on arrival in Britain. Several countries have been put on the “red” list, including India, meaning all arrivals must quarantine for 10 days in a government-appointed hotel at a cost of almost $2,500. Pubs and restaurants across Britain reported brisk trade as many opened for the first time since Christmas. Customers have been allowed in outside gardens and terraces since mid-April, but an unseasonably wet and cold spring has kept many away.  Reopening his Middle East-inspired “Nopi” restaurant in central London for the first time in six months, 36-year-old manager Pierre Malouf said he hopes the lockdowns are gone for good. “I’m nervous, excited, you know there's always a little bit of worry at the back of my head, but that's part of my job, but generally very positive. ...