A second lockdown would be an economic “disaster” for the UK, Boris Johnson has said.
Mr Johnson insists that reimposing nationwide restrictions would be “completely wrong for this country” and warns that the impact on the public finances would be “disastrous”.
However, the Government tightened restrictions on meeting in groups after a surge in infections prompted concerns over a second wave of coronavirus.
It is now illegal for people in England to gather in groups of more than six, and is the first time the Prime Minister has imposed a nationwide lockdown measure since restrictions began to be eased in May.
Senior Government sources said it would take two weeks to assess whether the rule of six had brought down infections. If it was found that it had failed to do so, further lockdown measures may be required.
It comes as hospital admissions are beginning to increase following a steep rise in virus infections.
A nationwide curfew, with pubs and restaurants closing early, has not been ruled out, while swathes of the North East of England have had tighter restrictions imposed, which include a complete ban on socialising with people outside of your household or support bubble.
Mr Johnson admitted that over time the rules "have become quite complicated and confusing".
Some areas of England are still in local lockdowns, but these are under constant review.
Here is the lay of the land following an update to the rules.
What are the new restrictions?
Social gatherings of more than six people are now illegal.
Anyone socialising in groups larger than six will be liable for a £100 on-the-spot fine, which will double on repeat offences up to £3,200.
The limit of six people from up to six households will apply to adults and children indoors and outdoors, in homes, gardens, parks and venues such as pubs and restaurants.
Announcing the new rules that came into effect on September 14, the Prime Minister said: "In England from Monday we are introducing the rule of six.
"You must not meet socially in groups of more than six. And, if you do, you will be breaking the law."
A family of five will only be allowed to meet one grandparent at a time, while families of six or more will be banned from meeting anyone at all.
Read more: What are the new North East local lockdown rules?
There will be a limited number of exemptions to the rule of six.
Mr Johnson said: "There will be some limited exemptions; for example, if a single household or support bubble is larger than six, then obviously they can still gather.
"Covid-secure venues like places of worships, gyms, restaurants, hospitality venues can still hold more than six in total. Within those venues, however, there must not be individual groups larger than six and groups must not mix socially or form larger groups.
"Education and work settings are unaffected. Covid-secure weddings and funerals can go ahead up to a limit of 30 people and organised sport will still be able to proceed."
What restrictions have been lifted most recently?
Wedding receptions of up to 30 people are allowed, and casinos, bowling alleys and skating rinks reopened. Beauty salons, tattoo studios and spas can offer all close “services and treatments”.
Plans to start indoor performances with socially distanced audiences and pilots of larger gatherings in sports venues and conference centres also resumed.
The final of the World Snooker Championship in Sheffield in mid-August was the first pilot event. Allowing spectators at sporting events was planned for October 1. However, that plan is now under review following a spike in positive Covid-19 tests.
In addition, indoor play and soft play centres have reopened, provided they introduce coronavirus-secure measures.
Read more: When will football stadiums reopen?
Will there be a second UK lockdown?
Mr Johnson insisted that reimposing nationwide restrictions would be “completely wrong for this country” and warned that the impact on the public finances would be “disastrous”.
The Government is keen to avoid a second UK lockdown. However, The Telegraph has learned that ministers are considering imposing a national "curfew" after hospitality venues in Bolton were ordered to close between 10pm and 5am. This followed a rise in infections.
Prof Whitty said the numbers of coronavirus case had been increasing much more rapidly.
On September 9, he told a Downing Street news conference that while the numbers among older people and children remained "flat", in other age groups there were "rapid upticks".
He said among 17- to 18-year-olds and 19- to 21-year-olds the numbers had gone up "really quite steeply" since mid-August, as the graph below shows:
And on September 17 the number of positive Covid-19 cases since the end of August had jumped by 167 per cent in England.
Mr Johnson said the new rules were being put in place "to prevent another wholesale national lockdown".
In an interview with The Telegraph in July, Mr Johnson insisted there would not be another national lockdown, saying the option was akin to a "nuclear deterrent".
On September 9, Matt Hancock refused to rule out a second lockdown, despite the assurances by the Prime Minister, following a surge in infections.
Speaking to LBC radio, the Health Secretary said: "Our goal is to avoid having to do anything more drastic by people following the rules."
But he would not rule out a return to lockdown, saying: "I wouldn't make a vow like that. You wouldn't expect me to - I am the Health Secretary in the middle of a pandemic where we are trying to keep the country safe."
But he added he "hoped" lockdown could be avoided: "The number of cases is largely driven by people socialising."
What about testing?
Testing is key to avoiding another lockdown.
However, large numbers of people will be refused coronavirus tests even if they have symptoms under Government plans to ration testing if the crisis deepens, The Telegraph revealed on September 16.
A prioritisation list drawn up by health officials suggests routine testing would no longer be offered to swathes of the public, with tests restricted to hospital patients, care homes, certain key workers and schools.
On September 9, Mr Johnson outlined plans to use testing to identify people who do not have coronavirus, so they can "behave in a more normal way, in the knowledge they cannot infect anyone else with the virus".
The "moonshot" plan, the Prime Minister said, could enable theatres and sports venues to test audience members on the day and allow in all those testing negative, as well as enable workplaces to operate more normally.
Mr Johnson said: "In future, in the near future, we want to start using testing to identify people who are negative - who don't have coronavirus and who are not infectious - so we can allow them to behave in a more normal way, in the knowledge they cannot infect anyone else with the virus.
"And we think, we hope, we believe that new types of test which are simple, quick and scalable will become available.
"They use swabs or saliva and can turn round results in 90 or even 20 minutes.
"Crucially, it should be possible to deploy these tests on a far bigger scale than any country has yet achieved - literally millions of tests processed every single day."
A pilot of the Moonshot Covid-19 testing programme will begin in October despite Government scientific advisers warning that it could be seen as "authoritarian".
Salford and Southampton have been chosen as the proving grounds for mass testing, with separate pilots to be carried out at sports and leisure venues such as football stadiums and theatres.
As of September 18, people in Northumberland, North Tyneside, South Tyneside, Newcastle Upon Tyne, Gateshead, Sunderland and County Durham are banned from meeting people who are not a part of their household or support bubble.
Hospitality for food and drink in these areas is also restricted to table service only, while there is a 10pm-5am curfew on pubs, restaurants and other leisure and entertainment venues.
Announcing the new measures, Health Secretary Matt Hancock said that parts of the region have seen "concerning rates of infection", with the incidence rate in Sunderland now at 103 per 100,000 population.
Households in Birmingham, Sandwell and Solihull have been banned from meeting each other since Tuesday, September 15.
It comes as cases in Birmingham increased rapidly.
Lockdown restrictions were eased on September 2 in Stockport, Burnley, Hyndburn, parts of Bradford, excluding Bradford city and Keighley town, parts of Calderdale, excluding Halifax, and parts of Kirklees, excluding Dewsbury and Batley.
The easing meant businesses that opened elsewhere on August 15, such as bowling alleys, would be allowed to open in those areas.
People living in those areas can also:
Hospitality venues are now restricted to takeaway only in Bolton as part of new measures aimed at curbing the spread of coronavirus in the town, Mr Hancock announced.
He confirmed that there would be a requirement for all venues in Bolton to close between 10pm and 5am, and that additional care home and hospital visit restrictions would be introduced.
A ban on mixing outside households in public outdoor settings will also be enforceable by law.
The Health Secretary also warned that social distancing must be “the first line of defence” in the fight against coronavirus, and expressed his concern about the recent spike in cases, driven largely by young people.
Caerphilly in south Wales was placed under local lockdown on September 8 while restrictions on household visits across western parts of Scotland have been extended and expanded to include East Dunbartonshire and Renfrewshire, with the next review scheduled for September 22.
A ban on two households mixing will continue in other areas under local lockdown, including parts of Greater Manchester, east Lancashire and West Yorkshire. There are also severe restrictions in Glasgow.
Residents have also been told to avoid using public transport except for essential travel.
Swindon and Sandwell will be given extra resources after becoming areas of enhanced support – the second-highest level in the Government’s three-tier approach.
And Stoke-on-Trent has been added to the watchlist for the first time as an area of concern.
In Northern Ireland, outdoor gatherings are now restricted to 15 people, while a maximum of six people from two households can gather indoors.
Going to work and using public transport
Mr Johnson is to press ahead with a campaign to get people back to the office despite the increasing rate of coronavirus cases.
Downing Street insisted there had been no change to the Prime Minister's advice that people should go back to their workplaces if they can do so safely.
However, unions have launched a fresh fightback against the return, claiming that fewer than half of workplaces have put adequate social distancing measures in place.
An information campaign in local and national newspapers encouraging workers to return to the office was delayed in the wake of concerns over a second wave of coronavirus.
In depth: Your rights if your employer asks you to go back to work
Face coverings are mandatory in shops, supermarkets, banks and building societies, with fines of up to £100 for anyone who fails to adhere to the new rules.
Speaking at a Downing Street briefing the Prime Minister said face coverings should be worn over your mouth and nose "if you're in an enclosed space, and in close contact with people you don't normally meet".
He added: "I know, wearing a face covering feels odd to some people I understand that, but face coverings do make it harder for the virus to spread, so please wear one to protect others."
The Government has introduced tougher penalties for repeatedly failing to wear masks in public places. Fines will double each time someone is found in breach of the rules, up until a maximum of £3,200.
On July 31, Mr Johnson announced that masks had to be worn in museums, galleries, cinemas and places of worship and this was written into law in England on August 8.
Visitors to hairdressers, gyms and leisure centres, dentists and opticians are not required to wear face coverings.
Hairdressers are, however, required to wear surgical face masks.
Face coverings are already compulsory on public transport.
The Government said on September 9 that people should always use the two-metre rule when engaging with those they do not live with - or one metre with a face covering.
There is also hope that at least some social distancing restrictions could be lifted by the end of the year.
Asked if Christmas was now effectively cancelled, Mr Johnson said: "Whether we are going to get things back to normal at all by Christmas, I'm still hopeful, as I've said before, that in many ways we could be able to get some aspects of our lives back to normal by Christmas.
"I talked just now about how you could do that. Through that Moonshot of daily testing - everybody gets a pregnancy-style test, a rapid turn-around test in the morning, 15 minutes later you know whether you are infectious of not.
"You may not know whether you are infected or not, but you know whether you are infectious, or not, and that gives you a kind of passport, a freedom to mingle with everybody else who is similarly not infectious in a way that is currently impossible."
Read more: What are the new social distancing rules?
People should continue to "limit social contact as much as possible, and minimise interactions with other households", Mr Johnson said on September 9.
The Government said people should keep their distance from people they do not live with, and encouraged meeting outdoors.
The rule of six replaces both the existing ban on gatherings of more than 30, and the current guidelines on allowing two households to meet indoors.
Mr Johnson said he was "sorry" that two whole households would no longer be able to meet if their total exceeds six people.
He said: "This rule of six will of course throw up difficult cases; for example two whole households will no longer be able to meet if they would together exceed the limit of six people and I'm sorry about that, and I wish that we did not have to take this step.
"But as your Prime Minister, I must do what is necessary to stop the spread of the virus and to save lives. And of course we will keep the rule of six under constant review and only keep it in place as long as is necessary."
However households and "support bubbles" that exceed six are exempt.
Families will be told to choose one member to visit elderly relatives in care homes.
New Government guidance for the care sector – which bans flowers and hugs – says homes can begin allowing visitors shortly after they have undergone risk assessments of safety protocols.
The advice recommends "limiting the numbers of visitors to a single constant visitor per resident, wherever possible". It says: "This, for example, means the same family member visiting each time to limit the number of different individuals coming into contact."
Relatives will be told to wear face coverings and follow advice on social distancing as much as possible, keeping at least one metre away and avoiding handshakes, kisses or hugs.
Individuals who test positive for coronavirus or show symptoms must self-isolate for 10 days.
The UK Chief Medical Officers extended the time period from seven to 10 days on July 30. They said that evidence - although limited - had strengthened, suggesting that individuals who were mildly ill with Covid-19 and were recovering had a real possibility of infectiousness between seven and nine days after illness onset.
In a statement published online, they said: "We have considered how best to target interventions to reduce risk to the general population and consider that at this point in the epidemic, with widespread and rapid testing available and considering the relaxation of other measures, it is now the correct balance of risk to extend the self-isolation period from seven to 10 days for those in the community who have symptoms or a positive test result.
"This will help provide additional protection to others in the community. This is particularly important to protect those who have been shielding and in advance of the autumn and winter when we may see increased community transmission."
The shielding programme, which was designed to protect the most medically vulnerable from the effects of coronavirus, ended. The Prime Minister said that the Government would "be sure to restart shielding at any point" if it was required at a regional or national level.
In depth: Coronavirus vs flu and cold symptoms
Grant Shapps, the Transport Secretary, published a list of countries and territories where the Government abandoned its 14-day quarantine policy.
Mr Johnson announced on September 9 that Border Force will also step up the enforcement of quarantine rules for travellers into the country.
"We will simplify the passenger locator form needed for travelling to the UK and take measures to ensure these are completed and checked before departure," he said.
"Border Force will step up enforcement efforts at the border to ensure arrivals are complying with the quarantine rules."
In depth: How to get travel insurance should you choose to ignore Foreign Office advice
Pubs, restaurants and hospitality
Hotels, pubs and restaurants reopened on July 4.
Social premises and venues, including pubs and restaurants, will be legally required to request Test and Trace information from customers and keep the details for 21 days, Mr Johnson said on September 9.
Mr Johnson said that he has tasked the Cabinet with increasing enforcement of the rules, adding: "In future, premises where people meet socially will be legally required to request the contact details of a member of every party, record and retain these details for 21 days and provide them to NHS Test and Trace, without delay, when required."
Fines will be levied against hospitality venues that fail to ensure that their premises remain Covid-secure.
The Government also announced it will "boost the local enforcement capacity of local authorities" by introducing Covid-secure marshals to help ensure social distancing in town and city centres, and by setting up a register of environmental health officers that local authorities can "draw upon for support".
Read more: What do the new Covid rules mean for gyms, pubs, restaurants and universities?
Gyms, swimming pools and sports
Gyms remain largely unaffected since changes were announced in September. However, the Prime Minister reiterated that groups of six people cannot go to the gym together.
Mr Johnson said: "Covid secure venues like gyms can still hold more than six in total.
"Within those venues, however, there must not be individual groups larger than six, and groups must not mix socially or form larger groups."
Swimming pools reopened and grassroots sports re-started so people of different households could train and play together. Clubs have to submit an action plan to the Government explaining how they will follow the rules.
Gyms and sports facilities opened again, with "enhanced cleaning", timed booking restrictions, reduced class sizes and spaced-out equipment.
While face coverings remain obligatory on public transport, gym-goers are not expected to wear theirs while working out. Some gyms might require them - so ask before you go.
The Government has said it will be reviewing its intention to return audiences to stadiums and conference centres from October 1.
In depth: Will gyms close again?
Mr Johnson said the Department for Education will issue guidance on how universities can remain open to students in a Covid-secure way, as they are told not to send students home in the event of an outbreak.
Among 17- to 18-year-olds and 19- to 21-year-olds the numbers have gone up "really quite steeply" since mid-August.
Speaking at the Downing Street press conference on September 9, he said: "Opening universities is critical, again, for students' life chances and, again, the health risks to individuals are low.
"Of course, many university students are in the age bracket where we have seen the infection rates rise recently as Chris (Whitty) was just explaining.
"My message to students is simple - please, for the sake of your education and your parents' and your grandparents' health: wash your hands, cover your face, make space, and don't socially gather in groups of more than six, now and when term starts.
"Today the Department for Education is publishing updated guidance for universities on how they can operate in a Covid-secure way, including a clear request not to send students home in the event of an outbreak, so as to avoid spreading the virus across the country.
"I am very grateful to universities for their continued cooperation and planning for the return of students."
Schools, nurseries and colleges opened "for all children and young people on a full-time basis" from September, with schools in England told to keep classes or whole year groups apart in separate "bubbles".
The Government insisted that closing schools "is not an option".
But Professor Whitty said the Government's policy on schools may have to be "looked at again" if infections among school-aged children rise.
Prof Whitty said: "At the moment rates are still very low, if there were to be a change in that, there were to be a much broader increase in rates including of school-age children, I think the current policies would have to be looked at again as in the other areas.
"But at this point, the rates in schools are very low. There will be some school outbreaks, but that is the current situation."
On August 28, the Education Secretary published new guidance that instructed schools to use rotas as a halfway house between teaching all pupils and teaching only the children of key workers if local lockdowns made it impossible to operate as normal.
Gavin Williamson said pupils would switch between classroom and home learning to “break chains of transmission of the virus” under a four-tier system.
Tier 1 schools are fully open to all pupils, but with the mandatory use of face coverings in corridors and communal areas for pupils in Year 7 and above.
Then, “if all other measures have been exhausted”, schools move to Tier 2, where secondary schools teach children on a rota basis and primary schools remain open to all pupils.
Tiers 3 and 4 cover schools returning to a system of teaching only the children of key workers, while remaining pupils are taught remotely.
All primary schools are encouraged to have bubbles that include a whole class, while secondary schools are likely to need bubbles that consist of an entire year group so the full range of subjects can be delivered.
Schools were advised to stagger break and lunch times, as well as start and finish times, to keep groups apart and avoid creating busy corridors, entrances and exits.
Students were advised to consider alternatives to public transport in the autumn.
Parents, staff and pupils are encouraged to walk or cycle to school if at all possible - and schools were told to consider using "walking buses" to reduce the use of public transport.
In depth: Will schools close again?
Hairdressers and salons
Hair salons reopened, but the experience of getting your hair cut is very different.
Hairdressers are required to wear full-face plastic visors and surgical face masks to reduce the risk of infection and also need to follow strict rules over the disinfecting of equipment.
Customers must usually make appointments, and there are limits on the amount of people in salons. Customers are not obliged to wear a mask, but can if they wish to.
Beauty salons, nail bars, tattooists, spas, tanning salons and other close contact services have also reopened.
In depth: What beauty treatments are allowed?
Hotels and camping
Hotels, holiday apartments, caravan parks and campsites can now operate as long as shared facilities are kept clean.
In government guidance released on June 24, establishments were advised to implement a series of measures to ensure the safety of guests and staff.
Those checking in to hotels should expect to see social distancing stickers on the floor, perspex screens at the reception desk and hand sanitiser or handwashing facilities as they enter the premises during their stay.
The duration of activities such as check-in should now be kept as short as possible, and keys should be cleaned in between guest use. Queues may form outside hotels like they have done outside supermarkets, and hotels have been asked to introduce queuing systems using barriers should they be needed.
Larger hotels can opt to stagger check-in and check-out times, or place markers on the floor to maintain social distancing.
Recommendations to stop coronavirus from spreading also include emptying mini bars, offering buffet-free breakfasts and regularly deep cleaning rooms, with 24 hours left between bookings.
All paperwork is likely to be removed from rooms, along with the telephone, while the plastic pouch containing tea and coffee sachets will either be removed or quarantined for up to 72 hours between guests.
It is thought campsites will ensure that tents are pitched further apart than normal so social distancing measures can be adhered to, along with frequent deep cleaning of facility blocks such as showers.
Some campsites will be required to reduce the number of pitches to keep numbers down.
Campsites in Wales reopened on July 6, while those in Scotland reopened on July 15.
Cinemas, museums, galleries and theatres
Boris Johnson announced on September 9 that plans to pilot larger audiences in venues later in September would have to be revised. Indoor performances resumed on August 15.
Britain's theatres, galleries and music venues will also receive a £1.57 billion rescue package. The Prime Minister described the arts as the "beating heart of this country" as he announced a package of grants in July amid warnings that many venues could fold without urgent government support.
Outdoor theatres reopened and other leisure venues, including cinemas, art galleries and museums were allowed to reopen more fully from July 4, albeit with their own social distancing rules in place.
Suggested guidance in galleries and museums includes one-way systems, spaced queuing, increased ventilation and pre-booked tickets. Wearing a mask is not mandatory. Cinemas are expected to sell only a certain proportion of seats for each movie and face masks are now mandatory.
Both the Cineworld and Picturehouse cinema chains have said film screenings will have staggered start and end times, and customers are likely to be required to queue outside before entering to maintain social distancing.
Once inside, families and friends who book together will be allowed to sit with each other at screenings, but it is likely that seats will be kept free between different bookings. However, there will be no pick 'n' mix or other self-service snacks.
In depth: This is what the Covid cinema experience is actually like
Bowling alleys, skating rinks and casinos
Casinos, bowling alleys and skating rinks reopened on August 15.
All of the above premises are expected to have "Covid-secure" measures in place, which will most likely involve limitations on customer capacity.
Places of worship are reopening, but hymns are forbidden due to the higher risk of the virus being transmitted through singing.
Churches are encouraged to implement a "booking system", meaning people may need to reserve their space ahead of services.
Worshippers are advised to bring their own bible or holy book to their place of worship with them. Where worshippers are unable to do so, books should be cleaned and quarantined for 48 hours since their previous use. Muslims should also bring their own prayer mat to services.
Communion is allowed if it is deemed "essential", but worshippers should not drink from the same glass or share the same bread, which could come pre-wrapped. The priest distributing communion should wear gloves and all those involved in the practice should wash their hands before and after.
No hymns should be sung or wood instruments used as they create an “additional risk of infection”.
For christenings and other water rituals, only “small volumes” should be splashed onto the body with full immersion avoided. Those present should stand “distant from any splashes” and all those involved should thoroughly wash their hands before and after such ceremonies. Parents should hold their children throughout the christening service.
The Archbishop of Canterbury, Justin Welby, confirmed that following social gatherings being restricted to six people, there is no change to guidance on places of worship.
Small weddings and civil partnership ceremonies can take place, with groups of less than 30. That number includes the couple, witnesses, officiants, guests, photographers, security or caterers. It does not include staff employed by the venue.
Those ceremonies will have to be staid affairs, as guests should avoid singing, shouting or raising their voices during the ceremonies, while the bride and groom must wash their hands before and after exchanging rings.
The guidelines also state that only one person is permitted to sing during the ceremony and they should do so from behind a perspex screen.
"Spoken responses during marriages or civil partnerships should also not be in a raised voice," the guidance says. "This is because of the potential for increased risk of transmission from aerosol and droplets."
Fathers may not be able to walk their daughters down the aisle unless they live under the same roof.
The orders of service will be disposable and cash donations will be discouraged, meaning those wanting to support the happy couple should do so online.
Under the new rules, weddings and civil partnerships should be concluded in the “shortest possible time” and limited to the “legally binding” sections of the service.
From August 15, receptions or parties after weddings were approved for up to 30 people, provided that they take place in "a Covid-secure way".