Johnson reiterated comments made by health secretary Matt Hancock on Monday (17 May) about UK residents not travelling to amber countries, such as Spain, Greece and France, for holidays despite this week’s reopening of international travel.

During a visit to a vaccination centre in London, Johnson said countries on the amber list were “not somewhere you should be going on holiday” and they should only be visited for “some pressing family or urgent business reason”.

“If they have to go to an amber list country, bear in mind that you will have to self-isolate, you’ll have to take tests and do your passenger locator form and all the rest of it, but you also have to self-isolate for 10 days when you get back,” added Johnson.

“That period of quarantine will be enforced with fines of up to £10,000 so I think it’s important to understand what an amber list country is.”

Johnson also said that he had so far seen “no conclusive evidence” to stop the planned further easing of Covid restrictions from 21 June, particularly around the emergence of the new "Indian variant" of the virus that is spreading through some parts of the country. But he admitted they would know "a lot more in a few days time".