CHRISTMAS will be the season to be "jolly careful", Prime Minister Boris Johnson has warned, as he continues to thrash out a plan with the leaders of Scotland, Wales and Northern Ireland which will allow families to reunite.

The Prime Minister was unable on Monday to confirm details of how people across the UK would be able to spend the festive period as talks continue between the devolved administrations.

However, he confirmed that England will return to a regional tier system from December 2, though details of which areas will be in which tiers will not be set out until Thursday.

The government has also announced that travellers arriving in England will be able to end their quarantine period with a negative coronavirus test after five days from December 15.

Transport Secretary Grant Shapps said passengers who arrive from a destination not on the Government's travel corridors list can reduce the 14-day period by paying for a test from a private firm after five days at a cost of £65-£120.

In a press conference on Monday evening, Mr Johnson said "we're not out of the woods yet" despite a breakthrough with a British vaccine, warning that the UK faced a "hard" start to 2021 but that he expected "things will look and feel very different" after Easter.

He said that with a "favourable wind" the majority of people most in need of a vaccination might be able to get one by April, as the Oxford-AstraZeneca team said its jab had proved up to 90 per cent effective.

It follows positive results from Pfizer and Moderna, but none of the jabs have yet been approved for use.

Mr Johnson, speaking via videolink at a Downing Street press conference as he continues his self-isolation, said: "We can hear the drumming hooves of the cavalry coming over the brow of the hill but they are not here yet.

"Even if all three vaccines are approved, even if the production timetables are met - and vaccines notoriously fall behind in their production timetables - it will be months before we can be sure we have inoculated everyone that needs a vaccine."

He warned that it is "not the moment to let the virus rip for the sake of Christmas parties", saying: "Tis the season to be jolly, but it is also the season to be jolly careful, especially with elderly relatives."

Mr Johnson said the months ahead "will be hard, they will be cold, they include January and February when the NHS is under its greatest pressure".

That pressure meant new tiers had to be introduced from December 2, replacing England's lockdown, with more areas facing tougher restrictions than under the previous regional regime.

Under the new system:

- People will be able to leave their home for any purpose, and socialise with others in outdoor public spaces, subject to the rule of six. But only in Tier 1 will people be able to meet indoors with those not in their household or bubble.

- Collective worship and weddings will resume, though with a cap of 15 guests, and in Tier 3 receptions will be banned. Thirty people will be allowed to attend funerals, but only 15 will be able to attend a wake.

- Pubs and restaurants in Tier 3 will only be able to offer takeaway and delivery services, while indoor entertainment, hotels and other accommodation will close. In Tier 2, hospitality must close unless it is operating as a restaurant and in Tier 1 it will be table service only.

- In areas where hospitality venues are allowed to stay open, the 10pm curfew will be replaced with a last orders call at 10pm – but venues must close at 11pm.

- Retail and personal care - such as hairdressers and beauty salons - can reopen in all tiers, and indoor entertainment venues – such as cinemas, theatres, bowling alleys and casinos – will be allowed to stay open in Tiers 1 and 2, but not Tier 3.

- Gyms and swimming pools can reopen everywhere, though restrictions vary across the tiers for classes and organised adult sport. Spectator sport – and theatre – will be permitted in Tiers 1 and 2, though only drive-in events will be allowed in Tier 3.

As well as the progress on vaccines, Mr Johnson pointed to the expansion of rapid mass testing as a way of returning to something approaching normality.

This could include greater freedoms for people who test negative and the prospect of daily tests replacing precautionary self-isolation for people who come into contact with an infected person.

While retailers welcomed the announcement that they will be allowed to reopen, there was fury in the hospitality and arts industries.

Kate Nicholls, of trade body UKHospitality, said: "Sadly, for many staff, it will be a Christmas out of work."