BORIS Johnson has insisted the discovery of the P1 Brazilian variant of coronavirus in the UK will not reverse the easing of the lockdown restrictions and knocked back Labour criticism, saying Britain had “one of the toughest border regimes anywhere in the world”.

Six UK cases of the variant, first detected in the Brazilian city of Manaus, have been discovered, three in Scotland and three in England.

This has led to accusations that stricter and quicker restrictions should have been imposed on international arrivals.

Matt Hancock, the UK Government’s Health Secretary, is expected to be quizzed on the subject when he leads a Downing Street press conference on coronavirus later today.

UK nationals or residents have continued to be allowed to return from Brazil using indirect fights and although they now have to quarantine for 10 days under supervision in a hotel, this policy was only implemented on February 15; around a month after concerns about the variant became widespread.

As authorities hunted one infected person in England with surge testing taking place in South Gloucestershire, where two individuals with the Brazilian variant have already been found, the Prime Minister’s spokesman pointed out that there had only ever been a “very few rare cases” where people arriving in Britain did not fill in the locator forms as required.

He said that the UK Government was in “regular” contact with Edinburgh but pointed out: “It’s a matter for the Scottish Government how they contact those individuals.”

Nadhim Zadawi, the UK Government’s Vaccines Minister, sought to allay fears, saying: “We would pick up community transmission of this variant very, very rapidly, because we are able to genome sequence so quickly.”

Yet Graham Medley, Professor of Infectious Disease Modelling at the London School of Hygiene and Tropical Medicine, who chairs a group of experts advising the UK Government, admitted there was always a risk with variants that “we might have to go backwards[on easing restrictions] and that’s what nobody wants to do…to actually open up and then have to close down again”.

But, when asked about Prof Medley’s remarks, the Prime Minister insisted the country was on a “one-way road map to freedom”.

He said: “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.”

No 10 also made clear schools in England would “reopen on March 8 as we set out in the road map”.

Mr Johnson stressed how there was a “massive effort” under way to prevent new coronavirus variants spreading.

“If you look at what we have done in the case of the South African variant, a massive effort went in there. The same is going on now to contain any spread of the Brazilian variant,” he declared.

The PM insisted there was “no reason not to think that our vaccines are effective against these variants of concern at the present time” and Public Health England “don’t think that there is a threat to the wider public”.

Insisting, the Government “moved as fast as we could” to launch its quarantine hotel policy, Mr Johnson told reporters: “We have got one of the toughest border regimes anywhere in the world for stopping people coming into this country, who may have variants of concern.”

Asked if the Government was too slow to implement quarantine hotel measures, the PM replied: “I don’t think so; we moved as fast as we could to get that going.

“It’s a very tough regime; you come here, you immediately get transported to a hotel where you are kept for 10 days, 11 days.

“You have to test on day two, you have to test on day eight, and it’s designed to stop the spread of new variants while we continue to roll out the vaccination programme.”

However, Sir Keir Starmer said the discovery of the Brazilian variant in the country showed the Government had not “secured our borders in the way we should have done”.

Speaking at a virtual meeting with Welsh businesses to mark St David’s Day, the Labour leader said: “It demonstrates the slowness of the Government to close off even the major routes, but also the unwillingness to confront the fact that the virus doesn’t travel by direct flights.

“We know from last summer that a lot of virus came in from countries where it didn’t originate in, but people were coming indirect, and that’s the way people travel.”

His Labour colleague, Wales’s First Minister Mark Drakeford, told the meeting he had “worries” about Mr Johnson’s plan for international holidays to resume in May for people in England.

“I would build the walls higher for now against the risk that we would bring into this country the variants that could be brewing in any part of the world, and could then put at risk all the careful work we have done to try and keep Wales safe,” he said.

Dr Deepti Gurdasani, epidemiologist at Queen Mary University of London, said the person who had fallen through the system “highlights failures in quarantine policy”.

She told BBC Breakfast: “Sage has also advised that, unless we had a comprehensive, managed quarantine policy at our borders, something like this would happen.

“But, unfortunately, it’s something that we’ve been quite complacent about; now we’re just seeing the consequences of that,” added Dr Gurdasani.

Yvette Cooper, who chairs the Commons Home Affairs Committee, told BBC Radio 4’s Today programme: “We need to look at how these cases have arrived in the country in the first place in order to prevent others doing so.”

The Labour backbencher said many travellers would have taken indirect flights from Brazil and that the situation highlighted “gaps” in the system.

She went on: “These cases seem to have arrived a month after the Brazil variant was first identified and we were raising with the Government the need for stronger action.”