OK, here goes.
Brexit was a Tory attempt to shore up the movement to the far right of that party. The far right had been there forever and one bane of many for that bunch of nutters was the EEC and then the EU. These guys were kept on the simmer all this time by Murdock's newspapers (him of Fox fame) to be brought out whenever that person thought the Tories were drifting out of orthodoxy. This is the general background that saw the PM Cameron state before the last election that if elected he would have a referendum on membership of the EU.Of course, the English not really using referenda unless they really have too, 3 in 50 years, had no idea what they were releasing. And what was thought would be an easy tool to gain more out of Brussels became the very mechanism for their exit. They thought they had control of it you see. and the tiny rump of Euro Sceptics that festered within the Tories would be stymied.
Of course what actually occurred was ALL the disaffected piled in and Voted Out. Not alone those that were inside the Tory party and the tory followers. It was as if Obama called a referendum on setting Roe -v- Wade within the US constitution thinking that the Pro Lifers inside the Democrats would be sidelined forgetting the Republicans entirely. Or at least underestimating the swing so much as to be criminal.
But why the split between rich and poor. For the most part that is so simple it's laughable. The poor don't go on holidays to foreign climes. And over the last 10 years the percentage that would call themselves poor increased hugely for the financial crisis obliterated whatever stability they had and whatever surplus that allowed them to holiday in Spain. Inside or outside just didn't matter.
Other aspects were entirely self inflicted. For 40 years the UK population was told every single petty little impingement was the fault of the EU. But the most egregious was what was occurring in counties that about 20 years ago started hi-labour fruit and veg farming. The touchstone on this was Boston in Lincolnshire.
There, large numbers of Poles and Lithuanians arrived to work in the glasshouses and the fields. Strawberry tomatoes and hand cut salad. This began as migrant labour, but soon became fixed. And here's the issue. Young people from the former east moved in together married had kids got sick and drove cars. In other words the population went up by 60% without an ounce of infrastructure being put in place by central government.
In fact, if they had decided to generate every factor that saw the rise of Hitler they couldn't have been more effective.This of course then entered all the other areas and cities where hospitals and schools were being rationalised (shut down).
But the funniest was the shock that the old people wouldn't give the government a kicking over changes to their pensions.
In the end, the 'liberals' simply didn't see it. They didn't get that their version of society had fallen short for 65% of the population. The Labour party is this very day trying to get rid of a leader elected by the membership with the largest majority ever. Why, well he didn't enter the fray with gusto, or at least the gusto expected by some of the Labour MP's in the Commons.