Britain has recorded its highest Saturday infection total in eight weeks with 1,012 new Covid- 19 cases.
The figures - which are more than 200 cases higher than last week - mark the biggest Saturday increase since 1,295 cases were reported on June 20.
Britain has now seen 317,379 positive diagnoses in total.
Concerns of a second major surge had been rising in recent weeks as local lockdowns sprung up in the Midlands and North of England, and Boris Johnson said he must 'squeeze the brakes' on easing rules at the end of July.
Yesterday, another 1,441 cases of Covid-19 were reported in the biggest one-day jump for two months.
The rising numbers of positive tests have ignited fears that the virus is rebounding and sliding out of control.
But top experts have dismissed concerns and believe the spike is merely down to more targeted testing in hotspots.
Government scientific advisers yesterday revealed Britain's coronavirus R rate remains between 0.8 and 1.0 for the UK and England overall - meaning it hasn't changed in the past week.
But the South East is now the only region where officials are confident the rate is lower than the dreaded level of one.
Britain has recorded its highest Saturday infection rate in eight weeks with 1,012 new Covid- 19 cases bringing the the UK's total deaths during the pandemic to 41,361
Three people who tested positive for coronavirus died across all settings today - which covers deaths in care homes, hospitals and the wider community
SAGE also admitted it is not certain that the R is below one overall because it can only use data from two to three weeks ago, and warned there are 'early indications' that the rate of spread could be increasing. Cases have increased by 65 per cent over the past week.
However, SAGE also maintained that the outbreak is shrinking and cases are falling by between one and four per cent each day in its growth rate update, which it releases every Friday alongside the R rate estimate.
Three people who tested positive for coronavirus died across all settings today - which covers deaths in care homes, hospitals and the wider community.
Scotland has reported no new deaths and Wales has reported one.
The figures came just hours after families were forced to make a last-minute dash across the Channel from France in a desperate bid to make it home before the government's 14-day quarantine kicked in at 4am.
From 4am onwards, all those arriving from France must quarantine for 14 days after the country reported a spike in coronavirus cases.
The 11th-hour move sparked chaos for an estimated 500,000 British holidaymakers in France - including a couple who forked out £1,000 for business class Eurostar seats and a family who drove for 12 hours to get home.
One mother was forced to leave two of her children behind with her husband when she fled France on the last Eurostar train.
The woman - who had to return to the UK before quarantine began due to her job - was only able to get tickets for herself and her baby.
She now fears her two daughters - who will return on Monday - may not be out of quarantine when their school goes back.
The woman, who did not provide her name, told Sky News: 'This has completely ruined our summer. I don't know what I'm going to do now. I am so upset about this.'
Others were forced to charter a fishing boat to make it home on time. The Dunedin Consort - a musical ensemble from Scotland - wrote on Twitter: 'Au revoir France! As exits from concerts go, this one is quite unique. We're sailing back to the UK on a fishing boat overnight to beat the quarantine.'
One family made it back to Britain with just hours to spare. Matt, a teacher from Manchester who did not share his second name, took his car on a Channel Tunnel train which was due to arrive back in the UK at 3.55am.
The 11th-hour move sparked chaos for an estimated 500,000 Britons in France with some forced to charter a fishing boat (pictured)
The Dunedin Consort - a musical ensemble from Scotland - wrote on Twitter: 'Au revoir France! As exits from concerts go, this one is quite unique. We're sailing back to the UK on a fishing boat overnight to beat the quarantine'
But some people weren't as lucky. Alexis Walmsley (pictured) from Basingstoke missed the last Eurostar train meaning both she and her disabled son now have to quarantine
Eurostar passengers arrive at St Pancras Station in London from Paris on the first train after a quarantine was put in effect for people returning from France
Travellers from France arrive at the Eurostar terminal at St Pancras International after France was removed from the list of safe countries people can travel to without going into quarantine
Eurostar passengers were seen in St Pancras Station in London after they arriving from Paris. They will now need to quarantine
His family had been camping in the Dordogne and had planned to come home on Monday but changed their tickets for an extra £115.
The family drove for 10 hours to Calais to catch the train and spent another £66 to stay at a hotel in the early hours before driving on to Manchester.
'We literally got on the last available train. We'd been keeping up-to-date with the chaos at Calais so we were fearing the worst,' the 40-year-old said.
'Luckily, once we got to Calais we sailed through and actually got back at just gone 3am.'
But some people weren't as lucky. Alexis Walmsley from Basingstoke missed the last Eurostar train meaning both she and her disabled son now have to quarantine.
She wrote on Twitter: 'So near and yet so far. Reorganised my return from France to ensure my disabled son didn't have to quarantine but our TGV was so delayed we are going to miss the last Eurostar home.'
She added: 'Made new booking for me and my disabled son (who won't understand quarantine) from Avignon to Paris for the Eurostar.
'We'd have made it home but for a massive delay at Lyon. Now I don't even know where we will sleep tonight.'
There are also fears that the new rules will cause thousands of children to miss the start of the school year as pupils who do not return to the UK by Tuesday night will still be self-isolating at home when the majority of schools go back on September 2.
But with limited capacity on flights, ferries and the Eurotunnel, many will have no choice but to stay in France – or pay high prices for some of the remaining tickets.
Some tourists had less time to avoid quarantine after the Scottish and Welsh governments demanded the rules be introduced a day earlier.
Meanwhile, France is likely to impose to impose tit-for-tat quarantine restrictions from Monday for people arriving from Britain, meaning British travellers will have to self-isolate on arrival there too.
Families made a last-minute dash across the Channel last night ahead of the 4am cut-off this morning when France was added to the UK's quarantine list. Pictured: A family arriving from Dieppe last night
Passengers disembarked from the penultimate ferry to Newhaven from Dieppe last night before the 14-day quarantine rules kicked in
People queue in line to check-in for a British Airways flight to Heathrow Airport on Friday at Nice airport, southern France
One family was seen cycling after getting off the penultimate ferry to Newhaven from Dieppe last night - before the quarantine rules kicked in
Meanwhile, France is likely to impose to impose tit-for-tat quarantine restrictions from Monday for people arriving from Britain, meaning British travellers will have to self-isolate on arrival there too. Pictured: A queue of cars fleeing France via the Channel Tunnel