What role did Karl Marx, the Bronte Sisters, the saxophone riff from Baker Street by Gerry Rafferty, and Enver Hoxha, dictator of Alabania, all play in the troubles in Northern Ireland? They were PhD subjects studied by paramilitary prisoners who became passionate and disciplined students. Kevin Connolly hears from three "lifers" and asks them if prison education has moderated their views or simply made them better-educated extremists.