Well if you belong to that persuasion you might have to think again, some recent evidence has emerged to support this Castle House Island.
According to reports this Island is located in Lough Key, the northwest of County Roscommon
, northeast of the town of Boyle.
Legends has it that the name Lough Key comes from the IrishLoch Cé. In Irish mythology, Cé was the druid of the god Nuada. He was wounded in the Second Battle of Mag Tuired and fled southward until he came to Carn Corrslebe, where he rested. He saw ahead of him a beautiful plain full of flowers. He sought to reach it, and when he did, he died. When his grave was dug there, a lake burst out of it, and flooded the whole plain, as you can see in the picture. It was thus named Loch Cé after him.
This lake is several kilometres across and contains over thirty wooded islands including Castle Island, Trinity Island, Orchard Island, Stag Island, Bullock Island, and Drumman’s Island. Castle Island has had a number of structures built on it over the centuries. The earliest record goes back to 1184, in the Annals of Loch Cé, where a lighting strike is reported to have started a fire in “The Rock of Loch-Cé,” a “very magnificent, kingly residence.” Currently a folly castle built in the early 19th century by the King family stands on the island. Trinity and Church Islands each have the ruins of medieval priories standing on them. Archaeology digs from c.2005-2012 found that the ‘folly’ seems in fact to be a remnant of several previous historic structures, like this Castle.
While this pictures might not be the real thing the fact is there was a Castle Ireland in Ireland