It’s not the author it’s the publisher who dreams up a catchy but crazy title. There has never been an Irish Pope.
You may never read The Irish Pope by Prof. Colin Barr because it is long, 500 pages, and expensive, £140. His subject is Paul Cullen who was the first Irish Cardinal and a very important figure in the 19th century blossoming of Irish Catholicism. There are fancier words to describe what he achieved; Ultramontanism, which I thought might be about a new currency to replace the US dollar, and the Devotional Revolution. But he was also called a Castle Catholic because he was in tune with old Irish Catholic families that wanted devolution (Home Rule) but not independence. The Bellews were in this camp and, not having a castellated castle, corrected this deficiency circa 1830.
After the abolition of most of the Penal Laws and Catholic Emancipation Ireland was ready for a religious revival and cometh the hour cometh the man. He has been described as being authoritarian and intransigent, in other words an awkward bugger, but I reckon he is the closest Ireland will have to a homegrown Pope.
I always supposed that they were called ‘Castle Catholics’ because, by the mid-19th century, they supplied much of the administrative staff at Dublin Castle.