I was arguing with someone on Twitter about Brexit recently – yeah, we’re still partying like it’s 2016 on that hellsite – when they happened to spot I live in Cambridge. Which, in their eyes, immediately invalidated anything I could possibly have to say about people in Britain’s left-behind communities. Because obviously, in this city, we all dress like Harry Potter and sit down every night to eat roast swan at ‘high table’. (Whatever that is. A table with really long legs, presumably?) Anyway, I tried to point out that there are working-class people in Cambridge, too (and that I might even b…