Video report by ITV News Health Editor Emily Morgan
An individual in the UK infected with the Brazil variant of coronavirus has been found, prompting praise from the Health Secretary.
The individual, thought to be one of six that tested positive for the new variant was found through contact tracing 379 houses in the South East of England.
The variant, first found in Brazil, has been identified as "a variant of concern" by UK health authorities.
Matt Hancock praised the "dogged determination" of health authorities and was forced to defend their amid criticism it had taken a week to identify the person.
Mr Hancock praised the use of "the latest technology" and "dogged determination" of the Test and Trace team to track down the individual.
"The best evidence is that this person stayed at home and there is no evidence of onward transmission but as a precaution we are putting more testing in in Croydon where they live to minimise the possibility of spread," he added.
Officials have been scrambling for several days to find the individual who, according to the PHE did not complete their test registration card when entering the UK so their contact details are absent.
PHE's Dr Susan Hopkins said the missing Manaus individual had been "interviewed extensively" after being found.
She added: "On Wednesday at 3pm, an individual phoned the 119 service. They were able to give the missing barcode number that they had held securely for the whole time.
"This individual has been interviewed extensively and lives within a household that had recently returned from Brazil and all had quarantined at home.
"Further precautionary testing will occur in the neighbourhood and we have already started testing all of the samples from the neighbourhood through whole genome sequencing to ensure there is no further distribution of cases in the community."
PHE was unable to give details on whether the person had been self-isolating but said that they are in the process of contact tracing all of the individual's contacts.
The government faced criticism after the PHE said on Sunday that six cases of the concerning P.1 variant were confirmed in Britain, three in England and three in Scotland.
The three Scottish cases are residents who returned to north-east Scotland from Brazil, via Paris and London, and subsequently tested positive for Covid-19, but are not thought to be linked to the cases in England.
Two were confirmed in South Gloucestershire but the third English case has taken weeks to track down.
The P.1 variant has been designated 'of concern' as it shares some mutations with the contagious South African strain.
A study on the P1 Brazilian variant among people living in the city of Manaus found potentially high levels of reinfection and suggestions it could be more transmissible.
A member of the government's Scientific Advisory Group for Emergencies (Sage) said the new strain, which has been designated a "variant of concern", could force the UK to "go backwards" in terms of relaxing restrictions.
How did health authorities locate the person?
Speaking at a Downing Street press conference on Friday, PHE's Dr Hopkins detailed how the person was successfully found.
She explained that the unnamed person, who lives in Croydon, south London, had attempted to register his test online, but “had failed to do so effectively”.
An investigation was launched and an "incident team of 40 people" began to trace the individual.
Tracing the test from it barcode, the team determined it had arrived at the Cambridge Lighthouse laboratory via the DHL service for home delivery.
This narrowed it down to two regions made up of 10,000 possible households.
Once the region and “time window” for the test were combined, experts tracked down “every single” distribution centre to filter down options.
An initial 379 potential households was scaled down to 27 individuals who received further calls and text messages.
Dr Hopkins said: “On Wednesday at 3pm, an individual phoned the 119 service.
“They were able to give the missing barcode number that they had held securely for the whole time.