“Groundhog Day” is back.

(Aaron Chown/PA via AP)LONDON – When Andrew Lincoln steps onstage at London’s Old Vic Theatre as Ebenezer Scrooge in “A Christmas Carol,” he looks out on an empty auditorium. The Old Vic is among theaters trying to keep the flame alive. That includes London, where theaters had just begun to reopen after a four-week national lockdown ended Dec. 2. The Old Vic has mounted an “In Camera” season of plays performed on its stage and broadcast online. Playwright Jack Thorne’s adaptation has been a hit at the Old Vic for the past three Christmases.