IT didn’t take long. Omicron, the Covid monster’s latest mutation, has been found in the UK.

Just three days after scientists in Pretoria alerted the World Health Organisation to the new variant, two cases linked to travel to Southern Africa were found in Essex and Nottingham. These follow a confirmed case in Belgium and suspected ones in Germany and the Czech Republic.

The individuals and their households are now self-isolating. Surge testing and contact-tracing is being carried out locally as is further genomic sequencing. Chances are, there will be many more cases in Britain in the days and weeks ahead.

Underlying the importance of the latest development, Boris Johnson, together with his two chief advisers on Covid, gave an impromptu Downing St press conference where new measures were announced, including extending booster jabs, all international travellers getting tested and having to self-isolate if positive and all contacts with an Omicron case having to self-isolate even if they have been double-jabbed.

The PM described the actions as “targeted and proportionate measures” to act as a precaution and “slow down the seeding” of the new variant and “buy time for our scientists to understand exactly what we’re dealing with and for us to get more people vaccinated and, above all, to get more people boosted”.

While there is still a good deal of uncertainty about Omicron, two key things emerged: it is highly transmissible - but what is not known yet is the extent of its “vaccine escape” ie how effective current inoculations will be against it - and that it can be passed to and from people who have had two vaccinations.

Boris avoided engaging his Plan B. People, for example, will not be asked to work from home – yet. But he did align England with the rest of the UK on face masks, signalling mandatory wearing of them on public transport and in shops.

The PM was obviously pressed on whether people were facing another heavily restricted Christmas but was coy about what might lie ahead, saying only with a grin: “I’m pretty confident this Christmas will be considerable better than last Christmas. That will do for the time being on that.” Of course, this is a pretty low bar.

It’s clear Operation Save Christmas is now underway in the Downing St bunker. After last year’s disastrous handling of restrictions in the run-up to the festive period, Boris - already under intense pressure from Tory colleagues to get his act together - is adamant that people’s Christmases will not be ruined again. Politically, any kind of lockdown would be disastrous.

Having temporarily banned flights from six Southern African countries, the PM is now seriously contemplating an expansion of the travel “red list” to more nations as the expectation is the new variant will in the weeks ahead spread its tentacles across the globe.

Indeed, by yesterday afternoon, four more - Malawi, Mozambique, Zambia and Angola – were added to it. Other countries like America and Australia are following suit.

From this morning, anyone travelling from Southern Africa will have to quarantine in a Government-approved hotel for 10 days and pay for the privilege; £2,285.

A Whitehall insider said: “We want to restrict travel to avoid restrictions at home. The PM and most of the Cabinet are in that place now.”

The travel industry is on tenterhooks, worried any more restrictions would set it back months just when bookings were reviving.

The latest chapter in the coronavirus nightmare comes as much of Europe is already implementing tougher restrictions due to a surge in infections. Tonight, Holland, struggling with a record-breaking jump in cases, becomes subject to an extended partial lockdown.

Not surprisingly, the South African Government, hoping to revive its summer tourism industry, denounced the UK’s move, complaining it was being “punished” for its swift action in alerting the world to Omicron.

Yet the approach by Johnson and other leaders is understandable. They have been politically burned by their past vacillations and need to show they are trying to get ahead of the Covid curve.

We have sacrificed too much not to learn lessons and take a prudent approach, which as Sir Patrick Valance, the UK Government’s chief scientific adviser, suggested meant going “sooner, harder and broader” than you wanted to.

Yet the messages from some scientists have been less than uniform or reassuring.

Some have branded Omicron “horrific” and the “most worrying” variant to date as it has double the mutations of Delta and appears more transmissable.

Others have insisted “this is not doomsday,” that current vaccinations could give a high degree of protection and, in any case, vaccines can be tweaked “very rapidly” to bolster protection.

Indeed, several biochemical companies are now working on doing just that to beat back Omicron.

Pfizer/BioNTech said, should the new variant succeed in overcoming the vaccines, it expected “to be able to develop and produce a tailor-made vaccine against that variant in approximately 100 days, subject to regulatory approval”.

AstraZeneca said that it had developed a “vaccine platform that enables us to respond quickly to new variants that may emerge”.

Of course, it is a truism that none of us is safe until all of us is safe.

Ex-PM Gordon Brown, who has called for a special international fund to provide sufficient vaccines to poorer countries, said it was “no surprise” Omicron had been discovered this week in South Africa and argued new variants were developing because richer countries were “hoarding” vaccines.

He said the UK’s failure to deliver 100 million vaccines, of which it had so far donated just 11%, was “probably the biggest international public policy failure of our times”.

Science, thus far, has been our saviour from experiencing a far worse coronavirus fate despite the fact that, to date, more than five million people have lost their lives to the virus.

Omicron could represent a significant milestone in the Covid journey. We can only hope that science comes to our rescue once again. The alternative is, frankly, too frightening to contemplate.