More than 40% of England’s population will be in lockdown from Boxing Day after a further six million people were placed under Tier 4 restrictions.

Health Secretary Matt Hancock said the variant coronavirus was spreading at a “dangerous rate” as he announced the measures, which include tough restrictions on mixing with people and the closure of non-essential shops.

He also said cases of another new mutant coronavirus linked to South Africa have been found in the UK and placed travel restrictions on the country.

The changes were made as Government figures showed a further 744 people were reported to have died within 28 days of testing positive for Covid-19, the highest such figure since April 29 during the first peak of the virus.

There were a further 39,237 lab-confirmed cases of coronavirus as of 9am on Wednesday, the highest figure reported on a single day throughout the whole pandemic – although this is in part due to much wider testing.

Areas moving to Tier 4 from Boxing Day are: Sussex, Oxfordshire, Suffolk, Norfolk and Cambridgeshire, those parts of Essex not yet in Tier 4, Waverley in Surrey and Hampshire – including Portsmouth and Southampton but with the exception of the New Forest.

Tier 4 restrictions include a warning to stay at home, a limit on household mixing to two people outdoors and force the closure of many shops, hairdressers and gyms.

The measures come on top of Tier 3 restrictions such as the closure of pubs and restaurants except for takeaways and deliveries.

Bristol, Gloucestershire, Somerset including the North Somerset council area, Swindon, the Isle of Wight, the New Forest and Northamptonshire as well as Cheshire and Warrington will all be escalated to Tier 3.

Cornwall and Herefordshire move from Tier 1 to Tier 2.

Mr Hancock told a Downing Street press conference: “Just as we had got a tiered system in place that was able to control this virus we have discovered a new, more contagious virus – a variant that is spreading at a dangerous rate.”

The changes means a total of 24 million people will now be in Tier 4, or 43% of the population of England.

Mr Hancock warned: “This Christmas and the start of 2021 is going to be tough. The new variant makes everything much harder because it spreads so much faster.

“But we mustn’t give up now, we know that we can control this virus, we know we can get through this together, we’re going to get through it by suppressing the virus until a vaccine can make us safe.”

The Health Secretary also set out details on the discovery of the “highly concerning” and “yet more transmissible” South African variant in the UK.

He said the two cases were contacts of people who have travelled from South Africa over the past few weeks.

The Health Secretary said the cases and their close contacts have been quarantined.

He announced immediate restrictions on travel from South Africa and the Government is telling those who have been to the country in the last fortnight and their close contacts to quarantine immediately.

The law will be changed to cover the new restrictions, he added.

The challenge facing the Government was underlined by official estimates showing the R value, the average number of people someone with coronavirus infects, has increased to 1.1 to 1.3, up from 1.1 to 1.2 a week ago.

The number of new infections is growing by between 1% and 6% every day, up from 1% to 4% last week.

Meanwhile, tempers flared in Kent as the French reopened the border to allow lorries to cross the Channel for the first time since emergency restrictions were imposed in response to the new variant.

More than 5,000 HGVs were being held in the county, with drivers being tested for Covid-19 before they are allowed to travel to France.

There were reports of disturbances at Dover and at the lorry holding facility in Manston involving those waiting to cross the Channel.

One man was arrested for obstructing a highway in Dover.

In other developments:

– Oxford’s Professor Sir John Bell said he expected regulators to approve the vaccine developed by the university’s scientists “just after Christmas” after it submitted its full data package for approval.

– Former prime minister Tony Blair said the Government should focus on distributing initial doses of the vaccine to as many people as possible without holding back supplies for a second jab.

– Care home staff in England will receive two rapid-result tests a week in addition to regular laboratory testing to help keep the new coronavirus variant at bay.

Trades Union Congress general secretary Frances O’Grady said the extra coronavirus restrictions would be “another hammer blow for struggling parts of the economy like hospitality and retail” and called for more support from the Government.

Confederation of British Industry deputy director-general Josh Hardie said “even more businesses face insurmountable pressure after such a tough year”.