Re your second marker, you say:
Second marker: that the Brexit conflict is a symptom of a nation fundamentally divided. London versus the rest of the country; Scotland and Northern Ireland against the English; the young against the old; the rural versus the urban; the privileged and supine metropolitan elite versus a marginalised middle class.
Today, these divides remain as absolute as ever. Two years of ferocious, incestuous debate seems to have left these divisions as deeply entrenched as ever. [here]
I agree with all this.
But it strikes me that the attitude of defeated Remainers and much of the media has been to brand all Brexiteers as "deplorables". Public intellectuals have been vicious in their denunciations of Leavers: “racist", "xenophobic", "ignorant" and so on.
Briefingsforbrexit.com said:
"It has become quite commonplace to associate support for Brexit with low levels of education and intellect and to claim that reason and thought inevitably lead to an anti-Brexit view."
This certainly hasn't been helpful to bridging the divides you identify.
The BBC had a great Intelligence squared debate on Brexit over the weekend. Covered 3 options: 1. The May Deal, 2. No Deal and 3. Second Referendum.
If I were British I'd be supporting 3.... and it seems to be gaining some traction.
If there is to be a second referendum, it would have helped if the Remainers had been a bit more gracious in defeat and recognised concerns of the Brexiters, concerns which go beyond trade and the economy.
Best,
Peter F.
Peter F.