Boris Johnson is expected to tighten Christmas coronavirus restrictions as a new strain of the virus is "spreading rapidly".

Spikes in coronavirus infections in London, and in parts of Sussex, Essex and Hertfordshire saw them all move to the very high alert level - but could they face even tighter restrictions?

What is Tier 4?

In August, the Department for Education published a four-tier structure, in which all educational institutions – including primary schools and early years settings – would be shut. 

On October 26, Health Secretary Matt Hancock told BBC Breakfast: "We've always said that we take nothing off the table. Having said that, we have seen the rise in the number of cases has slowed a bit.

"The problem is it's still going up, and while it's still going up we've got to act to get it under control. We rule nothing out, but at the moment the three-tier system is what we're working to and it's effective in slowing the growth of this virus but it hasn't brought this curve to a halt."

Government scientists including Prof Chris Whitty, the chief medical officer, warned that the "base line" Tier 3 restrictions were unlikely to be enough to bring down the R rate alone.  

A new strain of coronavirus in the South East that is potentially more infectious has only added fuel to the fire.

The Sunday Times Deputy Political Editor today tweeted the decision had been made to cancel Christmas for London, the South East and East, as areas are moved into new Tier 4.

It's likely that a “stay at home” message will be introduced by law.

A third national lockdown is a possibility, but an extra - and tougher - Tier 4 could be introduced for the worst-affected areas.

What areas are in Tier 4?

It's claimed that London, the South East, and East of England will be plunged into a stricter Tier 4 local lockdown.

More regions could be added as we head into the New Year amid ministers fearing that a new strain of coronavirus is "spreading rapidly".

The variant is said to be 50 per cent more contagious than the current strain.

What are the Tier 4 rules?

Those under Tier 4 restrictions will be expected to stay at home.

International travel is not advised.

It's likely that pubs and restaurants will remain closed.

It's unknown whether places of worship, hairdressers, and gyms will be affected as they were allowed to remain open under current Tier 3 restrictions.

When asked about what potential Tier 4 restrictions would look like, a Whitehall official told The Times: "There is a case for going further than Tier 3 and it is getting stronger.

"[That could mean] closure of non-essential retail, stay at home orders.

"That would have to be actively considered in conversation with the local authority."

When will we know more?

New measures could be announced in the press conference due to take place this afternoon at 4pm.

The prime minister will be joined by England’s chief medical officer Professor Chris Whitty and Sir Patrick Vallance, England’s chief scientific adviser.

An emergency meeting of senior ministers is taking place at lunchtime to discuss the new strain amid a rising number of cases in the region.

Professor Sir Mark Walport – a member of the Government’s Scientific Advisory Group for Emergencies (Sage) – said there was a real possibility that it could have a “transmission advantage”.

“What happens with viruses is they do naturally mutate all the time and the ones that are likely to do well are the ones that increase transmission,” he told BBC2’s Newsnight.

“We know that this is a new variant, it has been seen in other countries but it seems to be quite widespread which suggests that it has got a transmission advantage.

“Scientists are working extremely hard to work out what is going on. But it does definitely seem possible that this transmits more easily.

“It will make the social-distancing even more critical.”