Door-to-door testing will take place in Maidstone after a case of the South African Covid-19 variant was found.

Home Secretary Matt Hancock said that people living in the ME15 part of Kent, which covers much of Maidstone, are to stay inside and wait to be tested, although a map has since revealed it will not be the whole postcode area.

Speaking at this evening's Downing Street briefing, he said 105 cases of the South African variant had been found in the UK, with 11 which did not appear to have any links to international travel.

One of those 11 was discovered in the ME15 postcode area.

"We need to come down hard on it and we will," he continued.

"We have already made sure that all those cases are isolating and that we have done enhanced contact tracing of all their close contacts."

He said extra testing was taking place in those areas where the variant had been found.

"If you live in one of those postcodes, it's imperative that you stay at home and you get a test, even if you do not have symptoms."

"Working with local authorities, we are going door to door testing people in the local areas.

"If you live in one of those postcodes, it's imperative that you stay at home and you get a test, even if you do not have symptoms. This is so important so that we can break the chains of transmission of this new variant. We have got to bring this virus to heal."

He added: "The most important thing is that people in the postcode areas outlined need to take extra special precautions. It is absolutely vital that people in those areas minimise all social contact and get a test when the opportunity arises."

Mr Hancock said that "finding every single case" of the variant was the government's aim.

It was later clarified that essential workers could still go to work, shops will remain open and the existing lockdown rules will stay in place but residents should take extra care to avoid trips.

The strain was found in a person living in the town who had not travelled to South Africa or been in contact with anyone who had, suggesting community transmission.

In total, 105 cases have been detected in the UK but mostly in people with some link to the country, which is on the UK's 'red list' of countries from which returnees must quarantine in a hotel.

Public Health England's random checks uncovered several cases in the past week.

It was first reported earlier on that it just concerned two cases in Surrey.

Mobile testing units to swab everyone regardless of symptoms have been sent to Goldsworth Park and St Johns in Woking and later this week will head to Egham.

But now it has transpired there are 10 cases of concern relating to postcodes CR4, W7 and N17 in London; WS2 in the Midlands; EN10 in the east; ME15 and GU21 in the south east; and PR9 in Preston.

The government has asked for as many people as possible in the ME15 area to be tested, although Kent County Council published a map this evening showing which parts of the ME15 postcode would be tested.

A small number of bordering addresses in ME16 and ME17 will also receive tests.

Households within the area will be visited by staff from Kent Police, Maidstone Borough Council, Kent Fire and Rescue and other support agencies, who will knock on their door and ask everyone aged 16 and over to carry out a PCR test there and then; this test will then be picked up and sent for laboratory testing within a short time of the initial visit by the same team.

Residents should take this test whether they have symptoms or not. If residents have either just had a test – or are booked in for a test soon – it is important that they still take this test as additional sequencing for test positives will be undertaken.

Andrew Scott-Clark, director of public health for Kent County Council said: “We have been asked by government to help investigate whether this variant can be found in the ME15 postcode area after one person tested positive for this variant. By visiting houses door to door and offering a quick and easy PCR test, we can help restrict the spread of the virus even further, as well as testing all those samples for this South African variant.

“I would encourage everyone to play their part by taking this PCR test when it is offered and follow the usual advice around self-isolation if they test positive. I would like to reassure people that there is currently no evidence that the SARS-CoV-2 variant causes more severe illness, or that the vaccines being used will not protect against it. People across Kent should continue to follow the national restrictions that are currently in place.”

The extra surge testing carried out will be sent to laboratories for sequencing to identify whether the positive test results also test positive for the specific variant strain known as the South African variant.

Dr Alison Barnett, regional director at Public Health England South East, said: “The UK has one of the best genomic systems in the world which has allowed us to detect the variant originating in South Africa here in Kent and I urge everyone offered a test to take it up to help us to monitor the virus in our communities and to help suppress and control the spread of this variant.

“The most important thing is that people continue to follow the guidance that is in place – limit your number of contacts, wash your hands regularly and thoroughly, keep your distance and cover your face. If you test positive by any method, you must isolate to stop the spread of the virus.”

The South African variant is causing concern due to 21 variations which make it more transmissible.

But chief scientific adviser Sir Patrick Vallance says there is no evidence it is more infectious than the Kent variant, which caused panic before Christmas and led President Emmanuel Macron to close the border.

There is no evidence the vaccines being used are less effective against the strain.

Prime Minister Boris Johnson has said: "We are confident all vaccines that we are using provide a high degree of immunity and protection against all variants.

"The fact is we are going to be living with Covid for a while to come in one way or another. I don't think it will be as bad as the last 12 months – or anything like – of course, but it's very, very important that our vaccines continue to develop and to adapt, and they will."

For the latest coronavirus news and advice, click here.