Coronavirus rules are changing over the Christmas period to allow a limited amount of increased mixing.

Boris Johnson had promised “unanimous agreement” on the restrictions across the four nations, but the guidance is now different across England, Wales, Scotland and Northern Ireland.

What does the law say, and what can people do in different areas of the UK?

– What is the law?

Regulations currently allow for three households to form an exclusive “Christmas bubble” for the five days between December 23 and 27 across the UK.

However, on Wednesday the Welsh government said it will do things differently and legislate to cap bubbles at two households.

Politicians in England and Scotland have said while the rules will remain the same, they have changed their advice to recommend limiting social contacts as much as possible.

– What can I do in England?

The Prime Minister has told people to “have a merry little Christmas – and I’m afraid this year I really do mean little”.

While Mr Johnson said “we don’t want to criminalise people’s long-made plans”, he warned people should be “extremely cautious” when mixing next week and should minimise contacts in the days leading up to Christmas.

Updated guidance issued on Wednesday asks people to think carefully about whether they need to see elderly friends or family, or people who are “clinically extremely vulnerable”.

But the advice did not go as far as other nations and recommend limiting bubbles to two households.

– What about in Scotland?

First Minister Nicola Sturgeon said this week that her “strong recommendation” is for people not to mix households over the festive period to ensure what is “unequivocally the safest way to spend Christmas”.

Ms Sturgeon urged people to consider postponing their celebrations, or to meet with others only outdoors. She said if it is “essential” that gatherings take place inside, they should be for one day only with no overnight stays.

“The reality is that this Christmas simply can’t be normal. But we have every reason to hope that next year’s will be much more normal,” she said.

– What can people do in Wales?

First Minister Mark Drakeford first changed his advice for the Welsh public so “only two households should come together to form an exclusive Christmas bubble” over the five-day period.

A Welsh Government spokesman later said this change would be put into law.

The spokesman said: “It makes it easier, so we don’t have the position where the law says one thing and the guidance says something else.”

Mr Drakeford said: “The fewer people we mix with in our homes, the less chance we have of catching or spreading the virus.

“None of us wants to be ill this Christmas. And we don’t want to give coronavirus to our close family or friends.”

– What are the rules in Northern Ireland?

Ministers have agreed to a six-week lockdown starting on Boxing Day, following hours of discussions by the Northern Ireland Executive.

Measures will include closing all non-essential shops and confining the hospitality sector to takeaway services only. The lockdown will be reviewed after four weeks.

However there will be no changes to Christmas bubbling arrangements in Northern Ireland, meaning a total of up to three households may still mix.

Christmas regulations in Northern Ireland are the same as in England, other than anyone travelling to or from Northern Ireland has been given extra time to do so on December 22 and 28, but should only meet with their Christmas bubble between December 23 and 27.

– Will the Tier rules in England be lifted for the five days?

No, the restrictions will still apply over the Christmas period.

Pubs, bars and restaurants will still have to be closed in Tier 3 areas.

– Do the scientists think this is a good idea?

In a rare joint editorial, two health journals asked for the “rash” policy of easing restrictions to be cancelled.

The British Medical Journal and the Health Service Journal said the Government “is about to blunder into another major error that will cost many lives”.

Chief medical officer for England Professor Chris Whitty said the modelling is clear that any relaxation in the restrictions will lead to a higher death toll.

“Any kind of period where people come together in groups that otherwise wouldn’t meet leads to an increase in risks and that will lead to an increase in hospitalisations and deaths,” he said.