Every once in a while you meet a character on film who absolutely nails a certain type. Think John Cusack in High Fidelity or Reese Witherspoon in Election. You watch them on screen and say to yourself, "Yes, exactly. I know this person. I've met this person."
That's what Eddie Marsan did in Mike Leigh's Happy-Go-Lucky (2008), one of the great under-appreciated performances of recent years. We all run across this guy every couple of months at family get-togethers, around the office, listening to talk radio. Wound tight as piano strings, contemptuous of the happy, carefully cultivating a worldview in which they are the wise, persecuted hero, standing alone against mainstream society.
When Poppy asks him about this school years, that's the key. Bullseye. Watch Marsan when she brings it up. You can see an implosion occur somewhere in the deep recesses of his psyche.