The Orkneys and Shetland Isles
A pair of archipelagos lying due north of Scotland (the Orkneys just a bit to the north, the Shetlands further north and to the east), these are some of the most remote places in the British Isles. Combined, the two island chains have a population of just over 40,000 people, and in both cases only a third of the islands in the archipelagos are inhabited. Originally settled by Scandinavian colonists, today the islands are remote fishing backwaters, most notable for their abysmal weather (the Shetlands are just south of the Arctic circle and exposed to the worst that the North Sea can throw at them, the Orkneys are only marginally better), their neolithic heritage (Orkney has some of the best-preserved Neolithic sites in the UK), and their rich and still-extant folklore. The Orkneys in particular have a unique cultural tradition of trow and nuggles and worms and mermaids and selkies.
In fact, it is the last of these, the Selkies of Finfolkaheem that claim a certain negligent dominion over the islands. Finfolkaheem is the mythical homeland of the selkies (also called Finfolk), an island located in the Otherworld of the North Sea. From there, the selkies visit the islands, in search of silver, entertainment, and paramours. Theirs is a hands-off sort of rule, with very few laws. Don't hurt a selkie, don't hurt someone a selkie likes, and don't try to stop a selkie from doing what they want. Someone who wants to probably could, since the typical seal-folk is little tougher than a mortal man. But the selkie will have relatives, and the Finfolk are perfectly willing to exact bloody and gratuitous vengeance on anyone who crosses them, sinking ships, downing airplanes, and washing away villages. Their casual rule and the Orkney and Shetland's remote and underpopulated nature has made the islands a popular place for the more antisocial supernatural denizens of the British Isles, and there are lone wizards or fae hermits on some of the most distant isles. Though as the Fomorians from the Irish Sea do sometimes come visit, this kind of lifestyle is not without its dangers.