Eleuther or Elidyr Catraeth and York, fl 530s-550s.
There were two kings of the North with this name. Although the names are the same (the Roman and Celtic equivalents) over the years they have become known separately in order to avoid confusion (see Elidyr). Eleuther (also known as Eliffer) was the son of Gurgust. In the inter-dynastic rivalries amongst the sons and successors of Coel in the fifth and sixth centuries. Eleuther seems to have inherited or claimed the lands around York and Catraeth (modern Catterick). He is known as “Eleuther of the Great Army,” from which we can presume he was a powerful defender of his lands, particularly against the increasing waves of Angles who were settling in Northumbria in the mid sixth century (see Ida and Aelle). Eleuther was father of Peredur.

Geoffrey of Monmouth must have detected a whiff of these historical facts in his own History although they got lost beneath the delight of his own imagination. His Elidurus the Dutiful was one of the five sons of the heroic and unfortunate Morvidus, who was killed by a sea-monster. His eldest son, Gorbonianus, was a benign king under whose reign Britain prospered, but after his death his brother, Archgallow was a tyrant. He was deposed and his brother elidurus made king in his place. After five years elidurus encountered Archgallow wandering lost in the forests of the north and he forced his nobles to swear allegiance to Archgallo and accept him again as their king. Archgallo was a changed man and ruled wisely for ten years from his kingdom at York. After his death Elidurus returned to the throne but now faced an insurrection from his younger brothers Ingenius and Peredurus who dethroned Elidurus, imprisoned him in London, and then shared the kingdom between them. Ingenius died seven years later and Peredurus ruled alone, a good king who was fondly remembered. After his death, Elidurus was released and restored to the throne. he must by now have been very old. He was succeeded by an unnamed nephew, and thereafter Geoffrey rattles through the names of over thirty kings, few of whom are known amonst the historical recordss, although the much later ruler Samuil was probably his cousin Samwl. The fact that Geoffrey has Elidurus ruling from York rather than London suggests he was basing him upon the real king of this name.540