Allowing families or friends to meet outside is “pretty safe” and will not contribute “much” to the spread of coronavirus, a government scientific adviser has said.

Sage member professor John Edmunds said allowing two households to meet outside would have little impact on the Covid R rate, which measures the number of people, on average, that each sick person will infect.

It comes amid reports that Boris Johnson will allow one-on-one outdoor meetings between different households in March and later wider gatherings of two households outside, to allow families to meet at Easter, when he sets out his plan to lift lockdown restrictions on Monday.

Asked if two households socialising outside was likely to have any effect on the R number, Edmunds told BBC One’s Andrew Marr Show: “Not much, mixing outside is pretty safe.”

It came as health secretary Matt Hancock said Covid restrictions will be eased step-by-step, with weeks in between each relaxation.

Schools are the government’s priority and are scheduled to open on March 8 and Hancock said the government wants to see what impact children returning to the classroom has on infection rates before significantly easing other restrictions.

He told Times Radio: “Hence there will be weeks between the steps so that we can watch carefully.”

Hancock also said social distancing measures and the wearing of face coverings are likely to continue but hinted that they may not be legally required once more people are vaccinated.

He added: “I want to see it more about personal responsibility over time as we have vaccinated more and more of the population.”

Edmunds, a member of the Scientific Advisory Group for Emergencies (Sage), warned that disruption would continue in schools until children were vaccinated.

The prime minister on Saturday set new targets for vaccinating all over-50s by April 15 and all British adults by the end of July but did not mention children.

Edmunds said: “I think there’s an argument for turning to children (in the vaccine rollout) as fast as we can.

“I mean, I have two children myself, they are in secondary schools and I think that there has been major disruption at schools and there will continue to be major disruption in schools until we have vaccinated our children.”

Edmunds also warned that reopening schools would likely increase the R number close to 1.

If it rises above 1, it means the epidemic is growing again in the UK.

As of Friday, R was estimated to be between 0.6 and 0.9.

Asked if he would be more comfortable opening primary schools and then secondary schools later, Edmunds said: “Obviously I’m just sticking to the epidemiology rather than other needs. 

“Of course there’s great needs to get our kids back in schools as fast as we can. 

“But sticking to the epidemiology, yeah, of course, it’s always safer to take smaller steps and evaluate.”

Meanwhile, leading Tory lockdown sceptic Mark Harper said all legal Covid restrictions should be lifted by the end of April when all over-50s will have been offered their first vaccine dose.

“We think at that point people should be able to get on with their lives,” the chair of the Covid Recovery Group told Marr.

“The government may still give them health advice and there may be things people do voluntarily, but the legal restrictions should fall away at the end of April.”

He rejected suggestions that restrictions should be kept in place simply to prevent the emergence of new variants, which have more chance of mutating the higher the rate of transmission.

Harper said: “The way you protect against variants is our fantastic genomic sequencing programme and the fact that all of our vaccine developers will respond to changes in the virus by altering the vaccine – that’s the way you protect against variants.

“If we are going to say we are so worried about a future variant that might not be susceptible to the vaccine, that’s a recipe for never unlocking our economy and our society, and I don’t think that’s really an acceptable proposition.”