The vice president, it turned out, was giving a tour to Father Henry Stephan, the priest who baptised him in 2019, when Vance converted to Catholicism. It was the kind of moment Diarmuid Fionntain O’Scannlain might have been waiting decades for. O’Scannlain’s official job title is senior circuit judge on the US Court of Appeals. Informally, the 88-year-old devout Catholic son of parents from Sligo and Derry has acted as a talent scout and mentor for American conservatives. Most recently, he has played an important though indirect role in Vance’s rise from an impoverished youth to Donald Trump’s heir apparent....