Way back last May, Jonathan Van-Tam underlined his reputation for candour when he threw some scientific shade at the idea of 14-day quarantine for overseas visitors. Such a plan only “makes most sense scientifically…when incidence in the receiving country is low” and where people are coming from countries “where incidence is high”, he said.

Instead, a series of “travel corridors” were opened up in the following summer months, with Grant Shapps’ Twitter feed becoming the hottest must-have for anyone thinking of holidaying abroad. Sometimes with less than a day’s notice, people were told to get back home pronto or face staying at home for a fortnight.

Although the government is relying on the ‘Kent variant’ as an alibi for the third wave that hit the country in late December and January, we shouldn’t forget the causes of the second wave that began in October have been little explored so far.

It’s still unclear what impact last summer’s travel had in re-seeding the virus back in the UK after the first wave. The eventual public inquiry will want to assess that, along with the impact of the Eat Out To Help Out scheme, the return of students to universities and pupils to schools, and whether in some areas in the first wave lockdown measures were eased too quickly.

Thanks to bitter experience, Boris Johnson has perhaps now learned that when it comes to Covid, impatience leads to in-patients. Once a restriction is imposed, it has to be slowly and carefully lifted to assess any risks. Having taken some time to set up his new “hotel quarantine” programme, he suggested today that it would be in place for quite a while once it was finally up and running.

In an ironic twist, the PM even cited the Van-Tam principle from last year, saying: “They are most effective, border controls, when you’ve got the rate of infection down in your country.” The PM then acknowledged that you don’t need “foreign” imports to get hit by a new variant. “We in the UK are capable of seeing variants arise here – just in the UK, the Kent variant arose here – but that doesn’t mean we’re not going to be relying very much on border controls as we get the rates of infection down overall.”

Well, whisper it quietly but some MPs (Tory and Labour alike) are indeed still very sceptical about the effectiveness of the hotel quarantine plan, as well as the damage it will do to business and tourism in a post-Brexit ‘global Britain’.

The logistical challenge will be formidable (no contracts have yet been signed, No.10 revealed), and some wonder if the cost and effort will really make a material difference other than providing rhetoric (for both the government and Labour) on “strong borders”.

It’s not just the ‘Kent’ variant that proved we don’t need imports to trigger a fresh wave of infection. The fact that the Kent variant has itself mutated into a South Africa-style variant shows that home-grown dangers are potentially just as damaging. Similarly, the ‘Kent’ variant popping up in other countries may well be mutations of their own dominant strain.

Fortunately Van-Tam did have some good news today on the relative risks of those new variants. The deputy chief medical officer said the Kent variant, B117, has a “distinct transmissibility advantage” which allowed it to become dominant in the UK. But “early data” on “does not suggest that the South African variant has a distinct transmissibility advantage over our current virus”. If true, that would be quite a relief.

‌What this all means for voters’ summer holidays (and the economic shot in the arm many in domestic and overseas tourism industries are longing for) remains unclear. The PM’s suggestion that travel quarantine rules might be tightened further this year begs the question of when, if ever, those curbs may be lifted. It’s not entirely clear if the Home Office and Department of Transport are on the same page on all this either.

Van-Tam even appeared to pour cold water on Matt Hancock’s own plan to have “a great British summer” holiday with relatives in the UK. “The more elaborate your plans are for summer holidays..the more you are stepping into making guesses about the unknown,” he said. That actually sounded like a decent summary of Johnson’s own plans for hotel quarantine: a step into the unknown is indeed what it feels like.