I have found a story about very early royalty in the british isles and wondered if it is true.

the story says that a king named Arviragus on the british isles around 50AD, and that he caused so much trouble for the romans that Claudius I, emperor of rome, sent his daughter to marry Arviragus to bring peace. Claudius' daughter was named either Genuissa, Guinessa, or Genissa...which was the origin of the name Vanessa.

Geoffrey of Monmouth wrote a story of this happening, but his stories are known to contain some myths with some facts. there is also mention of an Arviragus in writings from rome in Juvenal 4.127, but this makes no mention of him being a king or that the daughter of Claudius was sent to marry him.

Supposedly, this same Arviragus gave Joseph of Arimathea land at glastonbury to build the first monastery in britain.