> Are you saying that the three key reasons for Brexit were not understood to be immigration, trade and the sovereignty of Parliament during the referendum
The link concludes: “as far as we’ve seen, Leave campaigners hardly mentioned the customs union in explicit terms at all, so there was generally little clarity about what leaving might mean in that regard.
“Campaigners did often say the UK should be able to set its own trade policy, and this could imply leaving the customs union as well... At the same time, though, certain sectors of an economy can be left out of a customs agreement, so it’s not a straightforward in or out issue.”
And of course, this rather unemotive summary leaves out all the context, where a remainer would say x means y, eg Brexit could mean leaving the single market, and leave would deny it and call it project fear.
I think the reasons for Brexit, as you put it, were in the eyes of the beholder. In my view, the reasons for Brexit boil down to English nationalism but you can put fancier labels on that if it makes you feel better. Not that you will get a consistent answer from different Brexiters, BTW. For some it, it might have been all these things. For some, it might have been only one or two. For many I expect, it was about winding the clock back to the 1950s.