John Weir is intimate with collusion. He’s now a businessman, living in South Africa, but in February 1977, when Sergeant Joseph Campbell was shot dead as he locked the gates of Cushendall police station, Weir was both a sergeant in the Magherafelt RUC Special Patrol Group and an active loyalist paramilitary. His seniors in the police, he says, were well aware of his dual role. “The RUC, and I suppose most police forces, it wasn’t a place where you could keep secrets, you know what I mean? You couldn’t be doing something and nobody knew about it. Do you think…