Blue St David’s Hall Monday 23 March 7.30pm BRITAIN’S best boyband Blue are back and are stopping off at St David’s Hall next Monday (23 March).   Since forming 2000, the boys have sold 40 million singles and 16 million albums worldwide including three No.1s of each format. Blue burst onto the UK music scene in May 2001 with the anthemic All Rise and were immediately on their way to pop stardom. Hit singles including Fly By, Too Close, One…