Gwen, the mother of Eigr, was the daughter of Cunedda Wledig, see Amlawdd and Gwen. Arthur is identified with Paternus on the Tintagel slate. The V. Paterni tells us that Paternus’s mother was a lady named Gwen (Guean) but does not give her ancestry. This is provided by late additions to the ByS, e.g. in version J:
Gwenn v’ch Karedic ap Kvnedda wledic
The respective pedigrees are shown below:
|Gen.||JC 7, ByA 31
Arthur’s pedigree may be reconciled with that of Paternus as shown by the column entitled ‘Reconciled’ in the table above. The name of the Paternus’s mother, Gwen, was, in fact, also an element of Eigr’s cognomen. The evidence for this assertion is provided by two Irish Arthurian Romances. In the RIA.23D 22 version of the Romance Eachtra an Mhadra Mhaoil (The Story of the Crop-Eared Dog) we have:
Artur mhic Iobhair mhic Ambros mhic Constaintin
whereas in the RIA.23M 26 version it is:
Arthur mhac Ambróis mic ConstantÍn mic Uighir Finndrea guin
In the Romance Eachtra Mhacaoimh an Iolair (The Story of Eagle-boy) the last name in the above pedigree takes the form Ughdaire Finndreagain. These pedigrees are consistent but need to be interpreted thus:
|Gen.||EaMM RIA.23D 22||EaMM RIA.23M 26||EMaI|
|-1||Iobhair||[Iobhair]||Uighir Finndreaguin||Iubhair||Ughdaire Finndreagain|
Iubair is the name given to Arthur’s father in the 1467 ms. The name Iobhair can take the form Iomhair which is derived from the Welsh Emyr Llydaw. This title referred to Petranus, Pedrwn or Pedr in Welsh, the father of Paternus. Thus, Arthur’s father, Iobhair (Pedr), was the son of Ambrois (Ambrosius) who also held the title Emyr Llydaw as shown by ByS 21. His father was Constantin (Custennin Gorneu).
Moreover, Arthur’s mother was Uighir Finndreaguin (Eigr Gwendragon), where Irish Finn and Welsh Gwen have the meaning white or fair or blessed. Finndreaguin was erroneoulsy taken to be Cinndreaguin resulting in the matronymic Arthur m. Uighir Finndreaguin becoming the false patronymic Arthur m. Uther Pendragon.
Allocating Ambrosius to gen. -2 is consistent with HB 42 which indicates he was one generation later than Vortigern and also with HB 66 which says the discord between Vitalinus and Ambrosius occurred 12 years after Vortigern’s reign.