The Prime Minister has warned people to be "responsible" when going outside and to "shield" the vulnerable people in their lives from the coronavirus.
Speaking in a press conference this afternoon, Boris Johnson explained how people should act to slow the spread of the disease.
Before outlining how the most vulnerable should be protected, the Prime Minister gave guidance about going outdoors on a sunny Sunday on which large groups congregated in parks across the country.
Mr Johnson said that the ability to go outdoors for exercise was extremely important for physical and mental wellbeing but that people needed to do it "responsibly".
Parks and other green spaces would not be closed he said, but people needed to practice social distancing even when out in the fresh air.
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People should stay away from large crowds of people and keep two metres from people where possible.
"Many many people do not have access, let's face it, to private green spaces where they can do that and that's why parks, open spaces are so absolutely crucial for our country and for our society," he said.
"But when we do that we have to do that responsibly... my message is you've got to do this in line with the advice, you've got to follow the social distancing rule - keep two metres apart.
"Otherwise if you don't do it responsibly... as you suggest there is going to be no doubt that we will have to bring forward further measures and we are certainly keeping that under constant review."
Keeping Britain's parks and green spaces open had more health benefits than locking their gates, he suggested.
Mr Johnson said: "The health benefits for the whole of society of keeping the parks and playgrounds open... outweigh the epidemiological value of closing them."
Dr Jennie Harries, Deputy Chief Medical Officer, said the public had a responsibility to make outside spaces safer by not congregating.
"There is a real balance point here - what we don't want to find is that we grow mental health problems or we grow other physical problems because of such a strict imposition," she said.
"The virus doesn't last well outside for all sorts of reasons around temperature, UV light and everything else so actually an outdoor environment compared with an indoor one is generally a safer one - but the difficulty is if people are congregating outside or coming together.
"A reasonably fit 70 year old who has been cooped up because he's safely isolating at home for a number of nights and wants to go outside for a bit of fresh air, and does so at a distance of two metres from somebody else, will no doubt boost his mental health and he'll no doubt feel able to tuck himself away perhaps for the next 23 and a half hours quite safely."
Dr Harries added people who were congregating were "dangerous" and making outside environments "unavailable" to others.
The Secretary of State for Housing, Communities and Local Government, Robert Jenrick, went on to explain how people should protect the most ill and vulnerable in their lives.
Those who are classified as extremely vulnerable, which may include young people with serious health problems, will receive a letter of advice from the NHS before March 29.
They are strongly advised to stay at home at all times and avoid any face-to-face contact for a period of at least 12 weeks from the day they receive the letter.
Essential support staff, such as carers, have been told they can continue visiting those most at risk until they begin to show symptoms.
All people who come into the homes of those most at risk must wash their hands for at least 20 seconds when they arrive, and then again at regular intervals.
The extremely vulnerable should also avoid gatherings, but should keep in touch with their loved ones via technological means.
Mr Jenrick said: ''I don't underestimate what we're asking of people. It will be tough.
''But if you are one of these people I want to assure these people on behalf of the Government that you are not alone.''
Mr Jenrick said the Government was creating a network of local hubs to deliver medicines by pharmacists to the most vulnerable and lonely people.
Groceries would be delivered by councils workers.
People who are not at risk themselves but live with someone who is should minimise the time they spend with them while trying to keep two metres away.
Separate sleeping arrangements should be made if possible and toilets and bathrooms should be cleaned between uses.
Meals should be eaten in different rooms, with dishwashers the ideal way to clean crockery and cutlery after meals.
The government also recommends everyone follows these basic principles of good hygiene:
- Wash your hands more often - with soap and water for at least 20 seconds or use a hand sanitiser. Do this after you blow your nose, sneeze or cough, and after you eat or handle food
- Avoid touching your eyes, nose, and mouth with unwashed hands
- Avoid close contact with people who have symptoms
- Cover your cough or sneeze with a tissue, then throw the tissue in a bin
- Clean and disinfect frequently touched objects and surfaces in the home
The government advice continues: "Shielding is for your personal protection, it is your choice to decide whether to follow the measures we advise.
"Individuals who have been given a prognosis of less than 6 months to live, and some others in special circumstances, could decide not to undertake shielding. This will be a deeply personal decision.
"We advise calling your GP or specialist to discuss this."
People who are considered extremely vulnerable are those with specific cancers, severe respiratory conditions, rare diseases, pregnant women with significant heart diseases and those on immunosuppression therapies.
The Government's full advice can be found here.
