The new tier, which will apply to all 32 London boroughs and the City of London, the east of England, which covers Bedford, central Bedford, Milton Keynes, Luton, Peterborough, Essex, and all previously tier 3 areas in the southeast, will mark the government’s latest and toughest restrictions.

Under the new tier, which will begin from tomorrow morning, there will be a “stay at home” order put into law, with people barred from leaving except to travel for education, childcare purposes and unlimited amounts of exercise.

The introduction of the new tier comes after Mr Johnson previously revealed that he did not want to revert to another nationwide lockdown because of the impact on the economy and people’s mental health prospects.

When do tier 4 restrictions go into place?

The stay at home order is in place from today, with people allowed to travel only for work, education, childcare or exercise.

From today, people living in other tier areas will also be advised not to enter tier 4 areas, with tier 4 residents not allowed to stay overnight away from home.

Individuals will still be able to meet with one other person in a public space outdoors in Tier 4 areas.

“Residents must stay at home. People must work from home where they can,” Mr Johnson said in a press conference on Saturday, with England’s chief medical officer Chris Whitty and chief scientific adviser Sir Patrick Vallance.

The exception to the rule will be support bubbles “for those at particular risk of loneliness or isolation,” the prime minister said.

Do businesses have to close and when?

Under the new restrictions, businesses including indoor leisure, indoor entertainment, and personal care are required to close. 

Nonessential retail businesses must close unless operating click-and-collect or delivery services.

Restaurants, bars, cafes and pubs must also close with the exception of providing food and drink for takeaway (until 11pm), click-and-collect, or drive-through or delivery.

 Supermarkets and pharmacies can stay open, as can repair shops, petrol stations, banks, launderettes and dry cleaners, medical and dental services and vet clinics.

A full list of businesses that must close and which can stay open under the new restrictions can be found here.

Will the restrictions be relaxed for Christmas?

Mr Johnson walked back previous plans for a five-day relaxed restriction period, explaining that Christmas gatherings will be banned in tier 4 areas, where people are barred from mixing with anyone outside their household.

Mr Johnson said there would be no relaxation of rules on New Year’s Eve.

How long will the tier 4 lockdown last?

According to the prime minister, the tier 4 measures will be in place for an initial two-week period and will be reviewed on 30 December.