What is "deruvian"

Deruvian , also known by several other names including Damian, was a possibly legendary 2nd-century bishop and saint, said to have been sent by the pope to answer King Lucius's request for baptism and conversion to Christianity. Together with his companion St Fagan, he was sometimes reckoned as the apostle of Britain. King Lucius's letter (in most accounts, to Pope Eleutherius) may represent earlier traditions but does not appear in surviving sources before the 6th century; the names of the bishops sent to him does not appear in sources older than the early 12th century, when their story was used to support the independence of the bishops of St Davids in Wales and the antiquity of the Glastonbury Abbey in England. The story became widely known following its appearance in Geoffrey of Monmouth's pseudohistorical History of the Kings of Britain. This was influential for centuries and its account of SS Fagan and Deruvian was used during the English Reformation to support the claims of both the Catholics and Protestants. Geoffrey's account is now considered wholly implausible, but Christianity was well-established in Roman Britain by the third century. Some scholars therefore argue the stories preserve a more modest account of the conversion of a Romano-British chieftain, possibly by Roman emissaries by these names.

Probably mistakenly, Deruvian's story has been given to the obscure St Dyfan thought to have been the namesake of Merthyr Dyfan and Llandyfan. His feast day does not appear in any medieval Welsh calendar of the saints and is not presently observed by the Anglican, Catholic, or Orthodox churches in Wales.