What I found particularly interesting in the blog was the idea that the brexiteers ignored geography, economics and history in preference to the concept that the British character would see them through the separation from the EU. Before World War I, the French army promoted the concept of "Elan Vital," which argued that the character, or the spirit, of the individual soldier was more important than any weaponry. I find those two ideas quite similar, basically arguing that character trumps any other consideration. The French, of course, found that Elan Vital only went so far in the face of German heavy machine guns and artillery. I suspect that British character will only go so far in the face of isolation from their natural market place, at a time when the rest of the world is moving to tighter regional integration, rather than isolation. There may be occasional exceptions created by temporary nationalist impulses, but I suspect those impulses will fade away or be torn away when the advantages of integration become more obvious -- if the UK sinks slowly into a long-term, grinding recession, as I think likely, while the EU continues to prosper, then other nations (like Poland) may come to look upon the UK as a good example of a really bad impulse.
There is really a massive flaw in that assumption about character: there is no such thing as national character, only of national indoctrination formats. I believe these to be skin-deep at best, and that when faced with reality rather than imaginary scenarios that call upon bluster and assumed machismo etc, people start to think for themselves. Which is pretty much what you have said here: "those impulses will fade away or be torn away when the advantages of integration become more obvious -- if the UK sinks slowly into a long-term, grinding recession," but sadly, short of a miracle, it will be too late. Also, with the rise of nationalism recently in several EEC states, it might well see the beginning of a wider unrest as more politicians see advantageous platforms for themselves in stirring up such nationalistic fervour as they exhort their own to follow the British example.
I also think that Europe falls victim to its own rules at times: regarding the closing of national borders which, depending on the state of infection in the individual countries makes perfect sense, both to contain what's already within as to keep out what may be worse outside - it's already prompted voices to say that that flies in the face of the open border principle of European integration, which is a nonsense: closing local borders for health reasons is not at all tantamount to reclosing them for political reasons, but the impression given is that some Eurocrats think politics trumps health. Looked at sideways, it's the same internal argument that has raged across America, Brazil as in many other countries: forget isolation - keep the economy going at all costs. And hey, there is little space between Trump and Bolsonaro when both pretend the pandemic is something that's been highly overrated, and both extol the virtues of hydroxychloroquine, a drug that's repeatedly been declared unsuited to the purpose. And guess what: they are now officially talking about testing it out on NHS staff in Britain! Is that a sop of solidarity towards Trump and South America as the electronic Brexit "negotiations" appear to be heading straight for the rocks?
I sometimes think that this modern world of instant communication/information/misinformation has brought more harm to us than good. Perhaps if they had all been left out of the constant media spotlight, rather than the crap we have to deal with now, politicos and doctors and researchers would have got on with the real job rather than waste time, effort, resources and national patience and create anxiety with the need for constant updates even when there are none to give. It can't create a good, productive working environment when progress becomes a race for publicity instead.