According to the government’s roadmap, 17 May is the earliest date from which international travel will resume, subject to the forthcoming report by the Global Travel Taskforce.

On Monday (5 April), Johnson said that when travel does resume, it will be governed by a new traffic light system with different entry requirements for arrivals based on the Covid risk in destinations colour-coded red, amber and green.

Arrivals from green list destinations are expected to still be subject to a pre-departure and post-arrival testing requirement, although the PM has hinted the standard for post-arrivals tests could be broadened to include cheaper lateral flow tests. Lateral flow tests are already acceptable for pre-departure tests.

Papers issued following the prime minister’s speech on Monday, though, urged holidaymakers not to book summer travel until the "picture is clearer".

Speaking during a visit to an AstraZeneca facility on Tuesday, Johnson said he understood people’e impatience.

"I do want to see international travel start up again," he said. "But we have to be realistic, a lot of the destinations that we want to go to at the moment are suffering a new wave of the illness.

"We can’t do this immediately, but that doesn’t mean we’ve given up on 17 May. We’ll be saying as much as we can, as soon as we can, about international travel.

"I know how impatient people are to book their holidays if they possibly can, but we just have to be prudent at this stage."

He added some form of vaccination evidence or certification would likely be sought by destinations.

"What of course we’re looking at is what several other countries are looking at and that’s the role of vaccination passports for overseas travel," said Johnson.

"I think that is probably going to be a factor of life. A lot of other countries are looking at that."