Boris Johnson has urged the nation to “behave responsibly” when pub gardens reopen and restaurants resume outdoor dining in a major easing of England’s coronavirus lockdown.

Shops deemed non-essential will also reopen on Monday, as will hairdressers, indoor gyms, swimming pools, nail salons and zoos in another stride back towards normality.

However, social mixing indoors will remain heavily restricted, with around two in five adults yet to receive their first dose of a Covid-19 vaccine and the vast majority yet to get both.

The Prime Minister urged caution during the “major step forward” as a scientist advising the Government warned the rules must be followed to minimise a possible rebound in case numbers.

“I’m sure it will be a huge relief for those business owners who have been closed for so long, and for everyone else it’s a chance to get back to doing some of the things we love and have missed,” Mr Johnson said.

“I urge everyone to continue to behave responsibly and remember ‘hands, face, space and fresh air’ to suppress Covid as we push on with our vaccination programme.”

The fanfare for the easing of restrictions has been muted by the national mourning for the Duke of Edinburgh.

Mr Johnson postponed his celebratory pint and Government communications have been pared back to essential messages after Philip’s death on Friday at the age of 99.

Meanwhile, Wales will also enjoy renewed freedoms from Monday, with non-essential retail reopening and border restrictions eased to permit travel again with the rest of the UK and Ireland.

Remaining school pupils will return to face-to-face teaching in Wales and Northern Ireland, in moves being echoed in Scotland as pupils return from their Easter breaks.

The “stay at home” order in Northern Ireland will also end as the number of people permitted to meet outdoors rises from six to 10.

Professor Peter Horby, chairman of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), told Times Radio: “The watchword has got to be caution really.

“It’s not clear exactly when or how big it will be, but there is, I think, inevitably going to be a bit of a rebound in the number of cases when things are relaxed.”

The Oxford University academic said the vaccination programme will minimise hospital admissions and deaths but warned it will not be completely effective.

“Now the extent of it really depends on how well we comply with the ongoing restrictions so we really have to take this step by step,” he added.

“I think we can be joyful and enjoy the freedoms but we’ve still got to realise there’s still a large number of people who’ve not been infected or vaccinated and so they will be at risk.”

Secret Spa co-owner Emily Ewart-Perks, who opened her beauty company’s at-home salon services up for clients at midnight, said Monday’s bookings are set to double the company’s best-ever day to date.

She added: “We realised we had quite a few regular clients who we weren’t able to book in on the first day back, so we thought ‘why don’t we open the first moment we can?’

“It’s so amazing. It’s just been such a long time coming.”

In England, pubs and restaurants have been making changes during lockdown to maximise their ability to serve customers outside.

But the British Beer and Pub Association estimates that just 40% of licensed premises have the space to reopen for outdoor service.

The previous 10pm curfew rule and the requirement to order a substantial meal with a drink have been scrapped, but social distancing must be observed.

In response to the easing of restriction, the Metropolitan Police said it will be “stepping up” patrols in high footfall areas from Monday.

Jane Connors, the Met’s Deputy Assistant Commissioner, said: “The Met is ready to welcome back people to the streets of London. We will be stepping up our patrols to busy high footfall areas, to look out for everyone’s safety and to disrupt any criminal activity.

“Of course, where we need to take action against those who dangerously flout the rules we will do. While the case rate has declined in London, we have seen the concerning position in northern Europe. It is important that we all stick to the rules so further lockdowns, or restrictions, are avoided.”

Domestic holidays can resume to an extent, with overnight stays permitted in self-contained accommodation, such as holiday lets and campsites where indoor facilities are not shared.

But these can only be used by members of the same household or support bubble.

International holidays remain banned until an unknown date, amid a row over the cost of testing.

People will not be allowed to visit each other’s homes, with socialising indoors still prohibited outside support bubbles.

It will be the third in a series of easings since the third national lockdown was legally imposed in England on January 6.

The next significant date is May 17, when socialising indoors will be permitted under the “rule of six” – if the Prime Minister judges that the vaccination programme is safely breaking the link between infections and deaths.

After three months of full national lockdown, the Government said on Sunday that a further seven people had died in the UK within 28 days of a positive Covid-19 test. Another 1,730 lab-confirmed cases were also announced.

Around 61% of adults have received at least one dose of the vaccine, according to official figures suggesting that more than 32 million people have received a jab. More than 14% have had both doses.

Mr Johnson welcomed a “record-breaking day” for second doses after figures reported on Sunday stated a rise of 475,230 jabs.