Brexit: Why they lost

Some of this is interesting, especially the substantive point that when Tony Blair (who on every important issue was John Major's pupil rather than his adversary) and his creepy cultural commissars tried to redraw the political map along ethical rather than pragmatic lines they made the mistake of de-legitimizing their opposition.

With the advent of the third way in the 1990s, it became fashionable in some quarters to declare that the adversarial model of politics was now obsolete – so categories of right and left were no longer needed. But even the champions of a post-political consensus cannot avoid drawing a frontier between themselves and their rivals. Since they refuse to draw it in an adversarial way, they create a moral divide, which does not permit a true agonistic debate. Tony Blair pitted the modernisers against the traditionalists; for Emmanuel Macron, the frontier is between the progressives and the conservatives.

[Chantal Mouffe in The Guardian, 'Centrist politics will not defeat Boris Johnson’s rightwing populism'] 

The result of this de-legitimization was a subsequent total lack of debate about a whole series of crucially important matters, from life issues to mass immigration to the hunting ban to gay marriage.
In the end of course the Left lost the Brexit vote mainly because they'd co-opted the European Union to the same cause as Sunday shopping and sodomy for teenagers. No attempt was made at any point to sell either a different vision of Europe (whether Christian, classical or ethnic) or to placate the opposition that had taken up the Euro-sceptic cause by conceding any ground at all on any single issue. We were simply told that we were "racist" and we were standing against the tide of history.

And in the end most people decided they'd had enough. They'd had enough of "cultural change". They'd had enough of being called "nostalgics" and "bigots" and "Little Englanders". They'd had enough of having their noses rubbed in it.

(But yes, the idea that the Left can stop populism now simply by having a "green new deal" does seem quite silly.)