Boris Johnson is under mounting pressure to order a widespread lockdown after thousands of people ignored calls for “social distancing” to slow the coronavirus pandemic.
The Prime Minister said he will be thinking “very, very actively” about what steps to take if people continue to gather in large numbers in defiance of calls to stay apart.
There was anger among MPs at scenes over the weekend of crowds flocking to parks, markets, beaches and beauty spots.
Conservative former Cabinet minister Julian Smith said he would support “any measure” the Government brought forward to force people to comply with the guidance.
For Labour, shadow health secretary Jonathan Ashworth said ministers should be making “immediate preparations” for the “next stage” while learning from other European nations.
The calls came as an 18-year-old was thought to have become the youngest victim of the virus in Britain as the number of deaths in the UK rose to 281.
In Walsall, a 36-year-old nurse and mother-of-three is on a ventilator in intensive care after contracting coronavirus.
Areema Nasreen is in a critical condition at Walsall Manor Hospital in the West Midlands where she works.
There are growing fears that Britain is on a similar trajectory to Italy – scene of the world’s worst outbreak – where the death toll passed 5,000 over the weekend.
The Italian government was one of a number of European countries to announce new or extended restrictions – with Germany banning public gatherings of more than two people not from the same household.
It comes as Health Secretary Matt Hancock has admitted there have been “challenges” with the supply of personal protective equipment (PPE) to frontline NHS staff after a doctors’ leader said they felt they were being treated like “cannon fodder”.
Amid reports that a number of medics are seriously ill after becoming infected with Covid-19, Mr Hancock said the armed forces were being drafted in to help distribute PPE supplies to the health service.
Meanwhile, respiratory doctors and nurses at Belfast Trust launched a video on Twitter saying people should stay at home to save lives.
One medic there says she has been a doctor for 35 years, adding: “I’m Susie, we are facing our greatest challenge and we are frightened … please stay at home.”
Mr Johnson has warned that the NHS could be “overwhelmed” in the same way as the Italian healthcare system has been, if the the spread of the virus in the UK is not curbed.
But at his daily No 10 press conference on Sunday, Mr Johnson indicated he was reluctant to ban people from going outside for a walk or to exercise because of the physical and mental health benefits, as long as they acted responsibly.
The Government later issued updated guidance making clear that essential travel did not include visits to “second homes, camp sites, caravan parks or similar, whether for isolation purposes or holidays”.
However among some MPs there was a clear mood for firmer action amid fears that further delay would cost lives.
Mr Smith, the former Northern Ireland secretary, said: “Many people have recklessly ignored government advice this weekend.
“I will support any measure the Government needs to force people to follow the guidelines designed to protect NHS staff and UK citizens’ lives.”
For Labour, Mr Ashworth said: “We urge the Government to make immediate preparations for the next stage and learn lessons from other European nations.
“If voluntary social distancing measures are not adhered to, the Government must bring forward their plans for stronger action.”
Labour MP Rosena Allin-Khan, who also works as an A&E doctor at St George’s Hospital in south London, also bitterly attacked the Government’s approach.
She said her latest shift had been a “deeply, deeply eye-opening” experience with previously fit and healthy people in their 30s and 40s “attached to machines, fighting for their lives”.
“The Prime Minister has been blase about this from the start, waiting for others to make decisions so he doesn’t have to. It is costing lives,” she said.
“Enough is enough. The NHS cannot cope and it won’t be long before doctors have to choose between who lives and who dies.”
While people were heading to open spaces, there were signs that city and town centres were closing down with Nando’s, Costa Coffee, McDonald’s, John Lewis, Primark and Timpson among the high street chains to announce they were closing their doors.
Meanwhile, letters are going out to 1.5 million people with underlying health conditions who are considered to be the most vulnerable to the coronavirus telling them to stay at home for the next 12 weeks.
The Government said it would ensure those without families and friends to support them would continue to receive food and medicines, with the military helping to organise deliveries.
Schools across the country will be opening their gates only to the children of key workers considered essential to the running of the country, with apparent confusion over how many will be admitted.
Education Secretary Gavin Williamson appealed to parents to keep their children at home unless their job is “critical” in the response to the coronavirus.
“This will help to halt the spread of the virus, protect the NHS and save lives,” he said.
“We will be closely monitoring what is happening in schools and will ensure they get the support they need in the weeks and months ahead.”