Welcome to C Day - where the "C" stands for the "complexity" of living with "coronavirus".

Because when the prime minister announces the return to something like normal living today, our revised way of life will feel anything but normal, and also bloomin' complicated.

For example, we'll be able to have friends or family inside our houses again.

But NOT friends and family from different households at any one time, just those from one household at a time.

And we won't be allowed to hug, and we can continue to socialise with up to five people from different households if we are outside, and if we live alone and we visit a household in a nominated bubble we will be able to hug.

It is the kind of systemic complexity that only young people with their flexible minds would be able to understand - or at least they would if their education had not been suspended.

Perhaps the most important reform today is that we are moving back to the nanny state and away from the coronavirus police state, in that these rules will be guidelines, not the law.

Or at least it's back to nanny for a while - because if there is a surge in coronavirus cases, there will be a return to some form of police-state lockdown, either local, regional or national, depending on whether NHS Test-and-Trace actually works.

What about the re-opening of swathes of the economy and our community infrastructure, from pubs to cinemas to hotels?

Well those pillars of our existence will feel open and thriving in the way that department stores were in Soviet Russia in the 1980s.

So when we go to the pub or restaurant, we are likely to have to leave our names at the door, just in case at some future juncture it turns out an infected person was sitting or standing nearby.

There'll be perspex dividers between tables. And even with dividers, we'll have to keep 1m from others. And if we can wear a face covering, so much the better.

But, you whoop, at least it's 1m not 2m - which means only half of hospitality venues will go bust for lack of business, rather than three quarters.

Maybe.

But even the 2m to 1m is not quite what it seems.

Because the distancing rule is most important in deciding who has to be quarantined under the track and trace system when we come into contact with an infected person.

Surely fewer of us will now face quarantine if the distance is an easier to sustain 1m rather than 2m?

Sorry. Not as simple as that.

We'll still be quarantined if we've been less than 2m from a Covid-19 sufferer for more than 15 minutes, UNLESS we're both wearing masks, or sitting side by side, or there's a perspex divider between us.

It could not be simpler could it?

I am so looking forward to the conversation with the tracer who rings me up to inform me that I have been in the dangerous proximity of an infected person and then we work out whether a gap of 1.75m for 17 minutes from an infected person who was wearing a face covering - when I can't remember if I was wearing mine - means go directly to quarantine, or not.

Forgive my facetiousness. This stuff is tricky, but then this virus is a wily bugger.

And every country in the world is facing the same horrendous calculus, namely how much to semi-permanently change the way of life, to reduce the risk of another surge in infection, while calibrating various restrictions on our freedoms by the differential cost to our prosperity, our income.

Against that backdrop, all the talk from distinguished former chancellors about how a VAT cut would make sense to stimulate economic activity is almost a joke - because when it comes to our massively reduced capacity to spend, at least as much of the problem is a supply constraint as inadequate demand.

For example, the boss of a huge retailer tells me that with social distancing, the maximum permitted number of people in their shops at any given moment has been reduced by 95%.

Maybe that falls to 60% or 70% with mask-wearing 1m. But it still means most of their outlets are kaput.

So when the PM urges you to do so, put on a face mask, go down the local, drink a couple of lemonade shandies and try to forget - that the humungous bill for this epidemic has yet to arrive or even be totted up.