The Delta coronavirus strain has started to dominate in favoured holiday locations in England as the prospect of foreign travel this summer begins to look decidedly gloomy.
Yesterday Boris Johnson announced that the lifting of lockdown measures would not take place this month as expected, but would be pushed back until July 19.
The PM said the country's "roadmap" out of restrictions had been derailed by the virulent Delta variant, which is now the dominant strain across the country.
While the coronavirus vaccines still work against the mutant strain, it is 40% more infectious than the previously dominant Alpha variant and 2.6 times more likely to hospitalise an infected person.
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With the likelihood of more countries being added to the green travel list within the month now looking unlikely amid the current case surge, many more Brits are expected to look at places to stay closer to home this summer.
An interactive map released by the Wellcome Sanger Institute shows what proportion of an area's coronavirus cases is the Delta variant.
In several UK locations popular with British holidaymakers the mutant strain, which first arose in India, is the dominant one.
Cornwall, which was expected to welcome in 400,000 guests during half term alone, has a Delta case proportion of between 78 and 100 per cent.
While the actual number of cases in the south-western county remains low, the presence of the highly infectious strain - along with huge numbers of holiday makers - is a cause for concern.
Lancashire, known for its rugged beauty and beaches, is another holiday hotspot with a high case proportion of the Delta variant, sitting between 80 and 100 per cent across the county.
The case count is much higher in Lancashire than in Cornwall, with Blackburn in the north-western county recording the second most cases - 500 per week - of anywhere in England.
Great Yarmouth in Norfolk, which offers long sweeping beaches and classic British seaside charm, has a 100 per cent Delta variant case rate.
Further south and around the headland into Kent, Canterbury has a 98 per cent proportion of Delta variant cases, as well as a stunning Cathedral and access to renowned oyster beds in Whitstable.
Those looking for a city break could do worse than Newcastle, which boasts the Angel of the North and the Tyne Bridge as well as world famous nightlife.
It now also has a Delta variant proportion of 64 per cent in the city and 84 per cent in nearby North Tyneside.
However, some parts of the country appear almost untouched by the Delta variant, and have endured zero cases in the two weeks to June 5.
They include popular destinations such as West Devon, New Forest, Hastings, Harrogate and Scarborough,
There have been at least 42,000 cases of the Delta strain in the UK so far since it emerged in mid-April.
That figure is only based on genetically screening around half of all positive tests, so the true number may be twice as high.
