The PM said there is currently no reason to change plans to start reopening England after three months of a third national lockdown. Schools and colleges are set to return to in-person learning from March 8, with restrictions on shops and businesses, pubs and gatherings being eased over the next three months – infection rates permitting.

Earlier on Monday, Prof Graham Medley, who heads up the government’s Scientific Pandemic Influenza Group on Modelling, told the BBC the discovery of the Brazilian variant might mean putting re-opening plans on hold.

However, responding to those remarks, Johnson said: “I haven’t heard that, and our whole strategy is to go forward in a way that is cautious but irreversible.”

“And we don’t think that there’s any reason on this basis to change that now,” the PM added.

There are currently six known cases of the variant in the UK and health authorities have tracked down five of those people so far. The hunt is on to try and find the sixth person who returned a positive test but failed to provide full contact details.

Health Minister Matt Hancock has issued a fresh appeal on Monday urging anyone who had been tested for Covid on either February 12 or 13 but who hasn’t picked up their results, to contact the National Health Service’s emergency line urgently.