Two new variants of coronavirus have been detected in the UK.
While there are only two cases of the newest discovery, the first new variant forced vast swathes of southeast England into a Tier 4 lockdown less than a week before Christmas.
More of the country will have similarly tough restrictions from Boxing Day and data shows the first new variant - named by Public Health England as VUI-202012/01 - has already been found across other parts of the UK.
While data provided by the COVID-19 Genomics UK Consortium (COG-UK) suggests that it has most commonly been found in London, Kent and parts of east England, the map below shows that it has travelled further.
Samples of the new variant have been found in other parts of England, South Wales, and in the Glasgow area.
The Welsh health minister has said the new strain is "seeded" right across the country, and Nicola Sturgeon has admitted that tougher measures may be needed in Scotland to contain the mutation there.
Jeffrey Barrett, lead COVID-19 statistical geneticist at COG-UK, told a Science Media Centre briefing on Tuesday: "They're relatively small numbers but I think it is important to be aware that it is certainly not the case that this is just completely geographically constrained to what is the current Tier 4 area."
The data on the new variant has been collected by COG-UK from 16 sequencing hubs across the UK, along with centralised data processing and research.
Samples come from Pillar 1 tests, largely from hospitals, and Pillar 2 tests, processed by Lighthouse laboratories.
Researchers stressed that the genome data does not represent all cases of the new variant, only those that have been processed and sequenced.
There is also a lag in the data due to the time taken to sequence the samples.
Cumbria's director of public health, Colin Cox, said in the district of Eden rates had risen to 345 cases per 100,000 people - the highest seen in the county to date.
"Only a small number of cases have been positively identified in Cumbria, but what is happening in Eden, which throughout the pandemic has had low levels of infection and now has the highest we've seen, points to something different going on," he said.
Lancashire's director of public health Sakthi Karunanithi said there was a "high likelihood" the new variant was in the county.
And Greater Manchester mayor Andy Burnham said that, while there was not yet any evidence that the strain has reached the area, public health directors "want to emphasise it is safe for people to assume that it is already here or it is about to arrive".
Cases of the new variant have been confirmed in Denmark, Italy, Gibraltar, the Netherlands and Australia.
France and South Africa also believe they have cases of the mutation, but these have not been confirmed.
At a Downing Street news conference on Monday, Sir Patrick Vallance - the government's chief scientific adviser - warned that more areas in England could soon see tougher restrictions due to spread of the variant.
Despite being judged to spread faster than the original strain, the government has said there is no evidence the variant is more lethal or causes more severe illness.
Meanwhile, the boss of BioNTech, whose company has developed a UK-approved COVID vaccine in collaboration with Pfizer, said he was confident the jab is effective against the new variant.