This post by Sigurd Towrie on the Wild Hunt legends of the Orkney Islands is a great follow up to Dan McCoy’s explanation I linked to about a year and a half ago. While McCoy focuses more on Norse folklore, Towrie leans more heavily on British/Celtic tellings of the legend:

But traditions of a Wild Hunt also existed in areas away from Norse influence.

In Wales, for example, the leader of the Hunt was Gwynn ap Nudd. The “Lord of the Dead”, Gwynn ap Nudd was followed by his pack of white hounds with blood-red ears.

These red-eared hounds are also found in northern England, where they were known as Gabriel Hounds. Their appearance was also a portent of doom.

In southern England, it was Herne the Hunter who led the hunt, while elsewhere it is also referred to as “Herlathing” – from the mythical King Herla, its supposed leader.

According to the 12th century write, Walter Map:

“This household of Herlethingus was last seen in the marches of Wales and Hereford in the first year of the reign of Henry II, about noonday: they travelled as we do, with carts and sumpter horses, pack-saddles and panniers, hawks and hounds, and a concourse of men and women.

“Those who saw them first raised the whole country against them with horns and shouts, and . . . because they were unable to wring a word from them by addressing them, made ready to extort an answer with their weapons. They, however, rose up into the air and vanished on a sudden.”