The Prime Minister Boris Johnson has announced that the country is moving to 'Plan B'.

He has issued tighter Covid restrictions, addressing the nation in the briefing room where his staff were viewed laughing about their Christmas party in 2020.

Johnson said that it was clear that Omicron - which has emerged on the back of a high rate of Delta infections - is spreading faster than the Delta variant, and that the 568 cases of the variant in the UK is almost certainly underestimated.

But what does 'Plan B' mean?

Here are the main points:

• Working from home - those who are able to must work from home from Monday

• Covid pass - evidence of vaccinations will be mandatory to get into nightclubs and venues where large crowds gather, including unseated indoor venues with more than 500 people and seated outdoor venues with more than 4,000 people and any venue with more than 10,000 people

• Face masks - they will be mandatory in public indoor venues, including theatres and cinemas from Friday

However, Johnson said that further measures could be considered.