The coronavirus lockdown restrictions in England are being introduced too soon and there could be another spike in coronavirus if measures are not adhered to, three leading scientists advising the government have warned.

Sir Jeremy Farrar, Professor John Edmunds and Professor Peter Horby, all members of the Scientific Advisory Group for Emergencies (Sage), which has been advising the government on the coronavirus outbreak, said ministers were taking risks by allowing the gradual reopening of shops and schools and larger gatherings to meet in private.

Professor Horby told BBC Radio 4’s Today programme: “We have been very successful in bringing it down, decreasing the numbers because of the social distancing.

“But, you will have heard that the R level is between 0.7 and 0.9, so it’s only a bit below one, so, we have got very little headroom, actually.

“And, it’s really important that we use that headroom very wisely and we don’t lose control again.”

Sir Jeremy said in a tweet that the newly introduced NHS test and trace system, which was launched on Thursday, should be “fully working” before measures were eased.

And a host of papers released by Sage revealed advice to the Government given in April said it was “likely” the R-rate - the average number of people which would contract Covid-19 from an infected person - was likely to rise above one should non-essential businesses reopen.

It comes as Britain is set for a weekend of high temperatures ahead of lockdown restrictions being eased which will allow up to six people to meet outside in England if social distancing is observed from Monday.

People have been told to listen to the existing coronavirus restrictions and advice during the weekend.

In the Twitter post, Sir Jeremy said: “Covid-19 spreading too fast to lift lockdown in England. Agree with John & clear science advice.

“TTI (test, trace and isolate) has to be in place, fully working, capable dealing any surge immediately, locally responsive, rapid results & infection rates have to be lower. And trusted.”

A graph showing the number of coronavirus deaths with Covid-19 in England. Credit: PA Graphics

A document on a Sage meeting from April 13, released on Friday, showed how the Scientific Pandemic Influenza Group on Modelling (SPI-M) that advises the Government warned against reopening shops and leisure facilities.

The document said: “There is limited evidence on the effect of closing of non-essential retail, libraries, bars, restaurants, etc, but it is likely that R would return to above 1 and a subsequent exponential growth in cases.”

Downing Street warned the public that the meet-ups remain prohibited until after the weekend, with Britain set for hot and sunny weather over Saturday and Sunday.

The Lake District National Park Authority has urged people to “show care and consideration for everyone who lives and works” in the area, while Dorset Police has told people to “go home or elsewhere” if an area looks too busy.

Chancellor Rishi Sunak denied that lockdown restrictions were being eased in a “reckless or big bang way”, adding: “We set out the five tests very clearly and because we are now meeting the five tests, because of the heroic efforts of everyone at home, the NHS, everyone, we are in a position to carefully and deliberately start to release the restrictions.

“I wouldn’t say that that’s happening in a reckless or big bang way, as the Prime Minister set out it’s been done in quite a measured and phased way progressively to make sure that we can keep an eye on things and we’re not running before we should.”

From Monday, groups of six people will be allowed to meet in England. Credit: PA

It comes after Mr Sunak said self-employed workers will be eligible for a second and final coronavirus grant.

Mr Sunak confirmed that employers must start paying towards the wages of furloughed staff from August.

Rishi Sunak said the schemes had been a “lifeline” for millions of people and businesses, but that as the country comes through the “other side” of the Covid-19 crisis, it was time to adjust them to “ensure those who are able to work can do so”.

Graphic detailing the easing of lockdown restrictions in England. Credit: PA Graphics

He has extended the self-employment income support scheme – which has so far seen 2.3 million claims worth £6.8 billion – enabling freelancers to access grants of up to £6,570 from August. Individuals could claim up to £7,500 under the first grant, which launched earlier this month.

And the Chancellor said that businesses will have to start paying National Insurance and tax contributions for staff in August, ramping up to 10% of furloughed wages in September and 20% in October.

Employees on furlough will keep getting 80% of their wages up to £2,500 a month.

Shadow chancellor Anneliese Dodds welcomed the extension, but said it was “concerning that there is no commitment within these plans for support to only be scaled back in step with the removal of lockdown”.

Coronavirus: Everything you need to know