The Health Secretary has urged the “small minority” of people who are breaking social distancing rules to change their behaviour, saying: “The more people follow the rules then the faster we will all be through this.”

Matt Hancock, who said he understood how difficult a time the country was having because he has lost two people he was “fond of”, added that the Government was “not planning any changes” imminently to the rules on exercising.

Earlier, Mr Hancock warned outdoor exercise could be banned if people continued to flout rules, as the coronavirus death toll rose sharply again.

It came ahead of a rare address from the Queen to the nation, in which she said if we “remain united and resolute” in the face of the outbreak “we will overcome it”.

The head of state warned the country “may have more still to endure”, but echoed the words of Forces’ sweetheart Dame Vera Lynne as she said: “We will meet again.”

Meanwhile Princess Alexandra Hospital in Harlow confirmed midwife Lynsay Coventry, 54, who died on Thursday, is the first serving midwife to die after testing positive for the virus.

Speaking during the daily press conference on Sunday afternoon, as the country prepares to enter its third week in lockdown, Mr Hancock warned people not to flout rules around social distancing and said tougher restrictions could follow.

He added: “Following these rules is mission-critical if we’re to protect the NHS, slow the spread and give the NHS time to expand capacity and so save lives.

“The more people follow the rules then the faster we will all be through this.

“So I say this to the small minority of people who are breaking the rules or pushing the boundaries: you’re risking your own life and the lives of others and you’re making it harder for us all.”

Mr Hancock said the Government is not currently looking at tightening the rules on exercising outdoors, after images of crowded parks over the weekend sparked public outrage.

“What we are doing is being absolutely clear that the current rules must be followed,” he said.

He said the rules are designed to include exercise to protect people’s physical and mental wellbeing.

The Health Secretary added it was unclear when the rules could be changed because of ongoing questions around whether those who have had the illness have developed sufficient immunity.

He said: “Even for those of us who have had it where the science predicts it’s likely that our immunity is higher and our ability to transmit the virus is lower.

“We are not yet confident enough how high the immunity is and how much lower the likelihood of those of us who have had the disease transmitting it is, to be able change the rules.

“The rules are the same for everyone and will be until the science can give us confidence that we can say something different to those who have been through it.”

Earlier, the Met Office confirmed Sunday as the warmest day of the year so far, with both Heathrow and Kew Gardens recording temperatures of 19.8C at 1pm.

Speaking at the press conference, Dr Jenny Harries, the deputy chief medical officer for England, said: “It is not just what you are doing but how you are doing it.

“If you are sitting on a park bench, people tend to accumulate – it is very difficult to prevent that.

“Having rules where we are getting all of the benefits and minimising the risks and harms is an important approach to maintain.

“We have set those rules, we are enforcing against those rules and we will reiterate those rules, because that is the best way to be able to bend the curve down and stop the spread of the virus.”

Mr Hancock, who returned from self-isolation on Friday after being struck ill with Covid-19, said he also offered his “profound sympathies” to the families and friends of those who have died.

He added: “I’ve lost two people that I was fond of so I understand what a difficult time this is for the country.”

The Department of Health said the number of coronavirus-related hospital deaths stood at 4,934 patients as of 5pm on Saturday, up by 621 from 4,313 the day before.

In other developments:

– Police reprimanded Scotland’s chief medical officer Dr Catherine Calderwood for visiting her family’s second home, against her own advice that all Scots should stay home.

– Professor Stephen Powis, NHS England’s national medical director, warned that while new cases of coronavirus appear to have stabilised, now is not the time to “take our foot off the pedal”.

– In Wales, a further 12 people died after testing positive for Covid-19, bringing the total number of deaths to 166, Public Health Wales (PHW) said.

– Ireland’s Health Minister Simon Harris said the Irish Government was aiming to almost double coronavirus testing to 4,500 a day.

– John Alagos, a 23-year-old NHS nurse, died after treating patients with coronavirus, his mother told the Mail on Sunday.

The eccentric Lord Bath of Longleat also died, aged 87, after testing positive for coronavirus.

– Two staff members at north London’s Pentonville Prison died after suffering Covid-19 symptoms, the Prison Officers’ Association (POA) said, while the Ministry of Justice said hundreds of risk-assessed prisoners within two months of their release date would be temporarily sent home.

– Newly elected Labour leader Sir Keir Starmer accused the Government of making “serious mistakes” in its response to the coronavirus crisis, but pledged to engage “constructively” with ministers.

– And Carrie Symonds, Mr Johnson’s pregnant fiancee, said she had spent the last week in bed suffering coronavirus symptoms, but was “on the mend”.

The Queen, speaking from Windsor Castle, personally thanked frontline NHS staff, care workers and others for “selflessly” carrying out their essential roles which had brought “us closer to a return to more normal times”.

And she said: “I also want to thank those of you who are staying at home, thereby helping to protect the vulnerable and sparing many families the pain already felt by those who have lost loved ones.

“Together we are tackling this disease, and I want to reassure you that if we remain united and resolute, then we will overcome it.”