Worrying maps reveal the speed at which the Indian Covid variant has taken hold in England, amid fears Boris Johnson may be forced to postpone "freedom day".
The mutant strain was dominant in 102 of England's 315 local authority areas by May 22 - having been detected in less than 30 a month earlier.
Data collected by the Wellcome Sanger Institute shows that the mutant strain - thought to be at least 20 per cent more transmissible than the one first detected in Kent last year - had been found in 65 per cent of towns and cities by that date.
In the 11 days since, it is expected to have spread still further.
Maps produced by the institute reveal the speed at which the mutant strain, called B.1.617.2, has taken hold across England.
Prime Minister Boris Johnson is under pressure to reveal whether his plan to unlock the country on June 21, the final date in his roadmap out of lockdown, will go ahead.
The data - the latest figures available measuring the spread of the new variant - show that parts of the North West, including Bolton and Blackburn, and the South East were worst affected.
The strain accounted for 80 per cent or more of cases in 20 local authority areas.
Areas where more than 80 per cent of Covid cases were the new strain in the two weeks to May 22:
- Blackburn with Darwen - 95.2%
- Croydon - 94.1%
- Central Bedfordshire - 92.8%
- Bolton - 91.3%
- Rossendale - 89.6%
- Bedford - 87.3%
- Lichfield - 85.7%
- Maidstone - 85%
- Burnley - 84%
- Canterbury - 83.3%
- Wigan - 82.4%
- Hillingdon - 81.4%
- West Lancashire - 80%
- South Ribble - 80%
- Pendle - 80%
- Tunbridge Wells - 80%
All cases in four areas - West Oxfordshire, Babergh, Sevenoaks and Dover - were found to be the Indian variant, but the overall number of infections were much lower than in Covid hotspots.
In the fortnight to May 22, the strain was detected at least once in 206 areas, and become the dominant one in 102.
Yesterday the Department of Health recorded zero Covid deaths for the first time since March last year.
In the past week there have been 43 coronavirus fatalities, a 10 per cent fall compared to the previous week, and a huge drop since the second peak in December and January - with more than 1,300 on a single day on January 19.
Downing Street has indicated that Boris Johnson still sees nothing in the data to suggest the plan to end all legal lockdown restrictions on June 21 will need to be delayed.
Asked about the Prime Minister's plans amid warnings over the spread of the Indian variant, a No 10 spokesman said: "The Prime Minister has said on a number of occasions that we haven't seen anything in the data but we will continue to look at the data, we will continue to look at the latest scientific evidence as we move through June towards June 21."
Most recent figures from Public Health England reveal that of 315 local areas in England, 211 (67%) have seen a rise in rates, 96 (30%) have seen a fall and eight are unchanged.
Blackburn with Darwen continues to have the highest rate, with 653 new cases in the seven days to May 28 - the equivalent of 436.2 cases per 100,000 people.
This is up from 303.3 in the seven days to May 21.
Bolton has the second highest rate, down from 452.8 to 375.2, with 1,079 new cases.
Rossendale in Lancashire has the third highest, up from 113.3 to 312.0, with 223 new cases.
The five areas with the biggest week-on-week rises are (shown in cases per 100,000 people):
- Rossendale (up from 113.3 to 312.0)
- Blackburn with Darwen (303.3 to 436.2)
- Ribble Valley (24.6 to 147.8)
- Hyndburn (77.7 to 175.2)
- South Ribble (26.2 to 111.0)
Education Secretary Gavin Williamson said recording zero deaths was "promising" but urged the public not to be complacent.
Speaking to LBC radio, he said: "It shows that the enormous sacrifices of the British people are starting to really deliver.
"The fact that the British people have gone out there with verve and gusto and actually got vaccinated when so many other nations have not had that same level of take-up is a real credit.
"It is promising what we've seen in terms of zero deaths but we can't be complacent.
"We continue to be careful and we've got to make sure we continue to get vaccinated."
Mr Williamson added that was a sense in Government that there had been "really promising progress" towards scrapping all restrictions on June 21, adding: "You're right to say it is about data, not dates, but the vaccines are having an impact in terms of actually reducing transmission, reducing the number of people in hospital and it is these factors that are going to guide the decision."
