Following a case of the new Covid-19 variant being identified in Brentwood, the prime minister has announced a strengthening of England’s rules.

This afternoon (November 27), Boris Johnson announced mask wearing will be mandatory in shops and on public transport, Omicron contacts will have to self-isolate and new arrivals will have to quarantine until they test negative for coronavirus.

The UK Health Security Agency has confirmed cases of the Omicron variant in Essex and Nottingham, which are both believed to be connected and linked to travel to southern Africa.

Initial reports suggesting the Essex case was in Chelmsford have since been corrected.

Brentwood and Ongar MP Alex Burghart tweeted: "Grateful to Essex City Council for briefing me this afternoon on the Omicron case identified in Brentwood. Local authorities are working at speed to identify and test possible contacts."

A spokesperson for Essex County Council said: “The individuals who have so far tested positive, as well as all members of their households, are being re-tested and have been told to self-isolate while contact tracing is underway.

“While this work takes place, it is important that everyone takes sensible precautions – get a PCR test if you have symptoms, isolate when asked, wear a face covering in crowded and enclosed spaces, ventilate rooms, get your vaccine and boosters as soon as you can.”

Malawi, Mozambique, Zambia and Angola will face travel restrictions from Sunday, when they will join South Africa and five other neighbouring nations on England’s red list.

Mr Johnson said: “We need to take targeted and proportionate measures now as a precaution while we find out more.

“First we need to slow down the seeding of the variant in this country, we need to buy time for our scientists to understand exactly what we’re dealing with, and for us to get more people vaccinated, and above all to get more people boosted.”

But the prime minister said border measures can “only ever minimise and delay the arrival of a new variant rather than stop it all together”, so all contacts with a suspected case of the new variant will have to isolate for 10 days, regardless of their vaccination status.

While the effectiveness of vaccines against Omicron is currently unclear, Mr Johnson said there are “good reasons for believing they will provide at least some measure of protection”.