Boris Johnson has cancelled Christmas for millions of people across London and south-east England after scientists said that a new coronavirus variant is spreading more rapidly.

The prime minister announced that from Sunday areas in the South East currently in Tier 3 will be moved into a new Tier 4 - effectively returning to the lockdown rules of November.

It means the relaxation to restrictions that he had previously announced have now been scrapped. We can no longer have three households meeting for Christmas.

What does Tier 4 mean?

* No mixing of households indoors

* You can meet one person from another household in an outdoor public space

* Non-essential shops, gyms, cinemas, hairdressers and bowling alleys will be forced to close for two weeks

The rest of England will also see the Christmas "bubble" policy - allowing up to three household to meet up over the holiday period - severely curtailed, applying on Christmas Day only.

Mr Johnson told a Downing Street news conference this afternoon that he was making the changes with a "very heavy heart".

He said: "I know how much emotion people invest in this time of year, and how important it is, for instance, for grandparents to see their grandchildren, for families to be together.

"So I know how disappointing this will be. But we have said throughout this pandemic that we must and we will be guided by the science.

"When the science changes, we must change our response."

The move comes after scientists on the Government's New and Emerging Respiratory Virus Threats Advisory Group (NervTag) concluded that the mutant strain identified by Public Health England - known as VUI2020/01 - was spreading more quickly.

People in Tier 4 will be told they should not stay away from home overnight and people from outside will be advised not to visit Tier 4 areas.

The new Tier 4 restrictions apply to all London boroughs.

Exemptions to the "stay at home" message which applied in the November lockdown, will also apply in the new Tier 4 - including support bubbles, childcare bubbles and children whose parents are separated.

People will be allowed to travel for education, childcare and to go to work if they cannot work from home and they will be permitted unlimited outdoor exercise.