Britain could implement tougher COVID-19 measures, including advice to work from home, as early as Friday, according to a government source cited by Times Radio on Thursday.

"Rumours abounding of an imminent Quad meeting to discuss imposing Plan B as early as tomorrow morning, meaning Working From Home and COVID passports for large venues. One source tells me it's '85% likely'," Times Radio presenter Tom Newton Dunn said on Twitter.

(Reporting by James Davey, editing by David Milliken)