The UK is heading for mandatory hotel quarantine - likely to be signed off for all arrivals to the UK by ministers tomorrow.

But it’s an incredible complex policy that is far from cost free. Much will depend on how tough the government decides to act. Some thoughts:

There are currently ~8,000 people a day coming into the UK. If all arrivals were funnelled through Heathrow, there are 10,000 beds in the vicinity so it would be filled within a day and half.

Which other airports/hotels will be involved? How could people be safely transported?

Ministers are assuming the number of people coming to the UK would reduce dramatically if hotel quarantine is introduced. But the logistics of keeping thousands of people isolated, fed and watered is vast. Even the smallest of gaps will undermine the whole strategy.

One option is to introduce a cap on arrivals, as has been done in Australia. Sydney allows just 1,505 arrivals a week, other cities are in the hundreds.

But as @sarahjnickson has pointed out, it has created an economic and human crisis in Oz. Flight prices have soared.

There are 30,000 Australian citizens stuck abroad who can’t return due to the cap and cost of flights/quarantine. Many don’t have work, are running out of money and have no hope of returning.

How will the UK ensure the same doesn’t happen here if we introduce quarantine for all?

And the UK is obviously not Australia - it is a far more interconnected country with its neighbours. How do you manage the Common Travel Area between Ireland and Northern Ireland? The necessary flows through Dover mean exemptions will be needed for hauliers.

There is also the question of an exit strategy: what will replace hotel quarantine? How long will it be in place for? Home Office would like to use GPS tracking for arrivals through an app or physical device for self-isolation at hone, but the tech isn’t ready.

If hotel quarantine isn’t lifted by the summer, you can bid farewell to a vast sum of tourism revenue. The cost for the aviation and hotel industry would be huge, even if Brits holiday at home, likely requiring another Treasury bailout to avoid total collapse.

Hotel quarantine may be a necessary policy as the UK continues pushes ahead of other countries in vaccinating its population - and the threat of new strain spreading become greater when lockdown is eased. Israel has gone one step further and banned all international flights.

It’s a quid pro quo that may prove popular with Brits: clamp down on borders and travel to open up society more quickly at home. But hotel quarantine is complicated, costly and has to be v carefully thought through. Hence why ministers are taking an extra 24 hours to decide.

Closing up the borders is also more Fortress Britain than Global Britain - not exactly the image Boris Johnson wants to project.

And how would hotel quarantine work the G7? Thousands of diplomats and politicians descending on Cornwall in June with Brits unable to travel.