In the 19th century, Edward Williams conflated him with St Deruvian, a figure in the legendary accounts of the baptism of King Lucius of Britain.

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.

[3] As late as 2010, it continued to promote itself as the oldest Christian settlement in Wales on the basis of Dyfan's supposed connection to the King Lucius legends.

[5] The only structure is a chapel of ease erected for visitors to the holy well nearby esteemed for treatment of paralysis and related illnesses.

This was known as Ffynnon Gwyddfaen or Gwyddfân[7] and Roberts argues against its connection with Dyfan "because the place was always called Llandyfân with the accent on the last syllable", appearing in earlier records as Llanduvaen.