England is in its third national lockdown after Boris Johnson shut schools to most pupils and imposed the toughest restrictions since March in an attempt to prevent the NHS being overwhelmed by surging coronavirus infections.

In a televised address to the nation on Monday evening, the Prime Minister pinned hopes on the rollout of vaccines to ease the restrictions in mid-February.

He ordered the country to stay indoors other than for limited exceptions and bowed to significant pressure to order primary schools, secondaries and colleges to move to remote teaching for the majority of students from Tuesday.

His move followed Nicola Sturgeon imposing a lockdown on Scotland for the rest of January, with a legal requirement to stay at home and schools closed to most pupils until February.

Schools and colleges in Wales will also remain closed until at least January 18 and move to online learning, while in Northern Ireland – which is already under a six-week lockdown – “stay at home” restrictions will be brought back into law and a period of remote learning for schoolchildren is to be extended.

In a bleak statement, Mr Johnson said the new variant of coronavirus, which is up to 70% more transmissible, was spreading in a “frustrating and alarming” manner and warned that the number of Covid-19 patients in English hospitals is 40% higher than the first peak.

“The weeks ahead will be the hardest yet but I really do believe that we’re entering the last phase of the struggle, because with every jab that goes into our arms we’re tilting the odds against Covid and in favour of the British people,” the Prime Minister said.

He said people in the top four priority groups would be offered a first vaccine dose by mid-February “if things go well and with a fair wind in our sails”, to allow restrictions to be eased.

It is thought that measures are unlikely to be relaxed until around 13 million people aged over 70 or classed as extremely clinically vulnerable have received the vaccine and been given enough time to be protected – about two to three weeks after getting the jab.

But Mr Johnson issued a series of ifs – on the public following the rules and understanding of the virus not dramatically shifting – before the nation can start “cautiously” moving down through tiered restrictions with schools reopening after the February half-term.

He told the public to follow the lockdown rules immediately before they become law in the early hours of Wednesday.

The regulations are expected to be published on Tuesday, while MPs will retrospectively be given a vote on Wednesday when they are recalled early from the Christmas break.

Labour leader Sir Keir Starmer said the measures are “necessary” and his party supports them, meaning that although Mr Johnson will want to minimise the scale of any Tory rebellion the Government is almost certain to win the vote.

The Prime Minister’s statement came after the chief medical officers for the first time raised the UK to the highest level on the Covid-19 alert system.

They warned the NHS was at risk of being overwhelmed within 21 days “in several areas” without further action.

Strong stay-at-home messaging has returned, with leaving only permitted for limited exceptions such as shopping for necessities including food and medicine and for work if it is impossible to do so at home.

Exercise will be permitted with household or support bubble members or with one other person from another household, but is advised to be limited to once per day and carried out locally.

Non-essential shops will have to close, prompting business leaders to call for fresh financial support to prevent a wave of closures and redundancies.

Exams will again face disruption as schools close to all pupils other than the children of key workers and vulnerable youngsters until after February half-term. University students will not be allowed to return to their institutions.

Mr Johnson said it is “not possible or fair” for all exams to go ahead this summer as normal, and said he understands the “inconvenience and distress” the late change will cause to millions of parents and that many will ask why he delayed the decision.

Restaurants and other hospitality venues can continue delivery or takeaway services but will no longer be permitted to serve alcohol.

Outdoor gyms, tennis courts and golf courses must close and outdoor team sports will be prohibited.

Premier League football and other elite sports with testing regimes and bubbles will be allowed to continue.

Ministers are understood to be considering toughening border controls to require international arrivals to have a negative test before travelling to Britain, with hauliers being exempt.

The extremely clinically vulnerable who were previously told to shield will be advised stay at home and only leave for medical appointments and exercise.

Mr Johnson said free school meals will continue while schools are closed, winning praise from Manchester United star Marcus Rashford who previously forced Government U-turns.

The fresh restrictions were imposed as ministers hailed the rollout of the new Oxford-AstraZeneca vaccine which begun when retired maintenance manager Brian Pinker, 82, became the first person to receive the jab outside clinical trials.

Scotland’s First Minister Ms Sturgeon announced a legally enforceable stay-at-home order for all of January in mainland Scotland and Skye.

She told MSPs: “It is no exaggeration to say that I am more concerned about the situation we face now than I have been at any time since March last year.”

Mr Johnson was alarmed by new data shown to him on Monday to suggest cases were rising rapidly in every part of England.

He said the number of Covid patients in hospitals increased by nearly a third in the last week to almost 27,000 – more than 40% higher than in April’s peak.