I was delighted to be invited to an exceptionally promising lunch - fine cooking guaranteed - in Wiltshire just before Christmas. Train schedules ordained that I arrived early, and this gave the hostess, an old friend, a chance to take me aside discreetly for a moment. "Don't," she said, "mention the B-word, for heaven's sake! They're all Remainers here. We don't talk about the war!"
Oh, the B-word! Brexit! Yes. Stella had voted for Brexit and her children had given her a hell of a time over it. "Is this what you want, mum? The total collapse of our jobs, pensions, way of life?" her son - working in the City of London - had railed over the phone. "Honestly, mum, you're awful!" "But, darling," Stella protested. "I just don't want England to be totally concreted over - as it will be if the population expands by five million every 10 years!" That led to accusations of the X-word - xenophobic, which Stella, fluent in three languages, is definitely not.
Anyway, I took her point, and much as I am tempted by a rattling good political argument, I refrained from the B-word.
A similar scenario has repeated itself with at least two other friends in London.
One, a literary soul, attended a high-end lunch party held by a powerful woman in the publishing world, who proceeded to enquire loudly: "Does anyone here know a single person stupid enough to have actually voted for Brexit?" Annie lifted a finger tentatively and said in a small voice: "I did."
The entire table rounded on her - it was like one of those HV Morton cartoons which portray the horrors of a unique social embarrassment.
As one, they chorused: "How could you!" One said: "Think of our house in the Dordogne. It's going to be ghastly now with the French neighbours."
Annie voted for Brexit probably because she is originally from Grimsby, a port in the north-east of England where the fishing industry has been devastated by EU policies. But in literary London she found herself in a minority of one.
Another pal worried anxiously that her Christmas card list was down - as were her party invitations - because her boyfriend was involved in the 'Labour Leave' lobby. "Honestly, Mary", she asked, "do you think I'll ever get another invitation from Dame Joan Bakewell?"
Some commentators have compared the huge social divide that has opened in Britain - and perhaps more specifically England - to the English Civil War, in which one side was characterised as 'Right but Repulsive' and the other as 'Wrong but Romantic'. Take your pick as to which are the Brexiteers and which the Remainers. And yet, on the plus side, it's stimulating to observe so many British people genuinely engaged in politics in a way that has seldom occurred - in my memory, anyway - in the past.
Down at the Dog and Duck they're as familiar now with Donald Tusk, Michel Barnier and Jean-Claude Juncker as they ever were with any domestic politicians. Anglophones have even learned to pronounced the French 'Jean' properly: like a soft 'John', rather than 'Jan' or 'Gene'.
The referendum brought more British voters to the polling booth than ever recorded. This is why generally left-wing online publications like Spiked are pro-Brexit: because it is all about The People.
Of course, it has shown up a class divide - as between the "anywheres" and the "somewheres", in David Goodhart's phrase (the anywheres feel at home in London, Berlin, Tuscany, LA, while the somewheres are rooted in their own communities).
It has revealed geographical divides, with London and the metropolitan areas pro-Remain, while great swathes of the north, the Midlands, the Scottish fishing areas, Cornwall and Wales are Brexiteer.
And, as we know all too well, it has been an education in the complexities and arithmetic of Northern Ireland and the border connection.
But it's still a national conversation which has engaged people in politics this year, and that surely is a stimulus to citizen democracy. As for the social embarrassments - well, actually, they usually work out fine. Most people have decent enough manners not to butt each other on the head when a political difference arises, although, true, if too much alcohol is partaken, inhibitions may be loosened.
But these differences also illuminate the fact that individuals do have different points of view and experiences, and that should be respected. That is what civilised society entails. We don't butt one another over the head: we exchange cordialities and try to smooth over dissonant notes. If that involves a smidgen of hypocrisy - so what?
Social media today can be ferocious, even rabid. People post dreadfully rude messages on Twitter - I've been called every kind of mad bat, thicko and bigot by people hiding behind hashtag pseudonyms. But face-to-face, the atmosphere changes. You're dealing with a human person in all their complexities. Edges soften. Sympathy is established, maybe through shared experiences. And human chemistry is unexpected: sometimes totally dissimilar individuals just hit it off.
The triumph of real, live, social interchange is tolerance.
Stella was reconciled with her son. Annie's knowledge of the fishing industry was taken on board by some of the literary folk. And Joan Bakewell is far too well-mannered to exclude anyone on grounds of political association.