Which British island is the home of the giant ghost dog, Moddey Dhoo?

The Moddey Dhoo (Manx Gaelic, meaning "black dog") is a phantom black hound in Manx folklore that reputedly haunted Peel Castle on the west coast of the Isle of Man. The Manx name Moddey Dhoo was transcribed as Mauthe Doog (/ˈmɔːðə doʊɡ/ by an influential 18th-Century English-speaking folklore source, which led to a history of misspellings of the proper name.

The English topographer and poet George Waldron seems to be the sole definitive written authority of this folklore localized in the castle. Waldron transcribes the original Manx name "Moddey Dhoo" as "Mauthe Doog", and describes the dog thus:

They say, that an apparition called, in their language, the Mauthe Doog, in the shape of a large black spaniel with curled shaggy hair, was used to haunt Peel Castle; and has been frequently seen in every room, but particularly in the guard-chamber, where, as soon as candles were lighted, it came and lay down before the fire in presence of all the soldiers, who at length, by being so much accustomed to the sight of it, lost great part of the terror they were seized with at its first appearance.