CASTLE DORE AS THE FORT OF UTHER PENDRAGON (A SELECTION FROM https://mistshadows.blogspot.com/2021/10/the-forts-or-settlements-of-gorlois.html)

[https://mistshadows.blogspot.com/2021/10/the-forts-or-settlements-of-gorlois.html]

A 'Caer Gwrlais' is right next to Castle Dore, a fort near where the famous Cunomorus/Cynfawr stone was found.  Cynfawr or Cunomorus was traditionally an ancestor of Geraint son of Erbin.  On the place-name Castle Dore from The Arthur of the Welsh: The Arthurian Legend in Medieval Welsh Literature (University of Wales Press, 2020):

The 'water' etymology is incorrect, in my opinion.  The word is plainly OE dor-weard (see the relevant entry in Bosworth and Toller), 'doorkeeper, porter.'  The word continued into Middle English (see https://quod.lib.umich.edu/m/middle-english-dictionary/dictionary/MED12396) where it meant the same thing, a gatekeeper or porter.  We are immediately reminded of the Arthurian poem, PA GUR, which begins with the famous line 'Pa gur yv y porthaur?' or 'What man is the gatekeeper?'

The following selection from https://d.lib.rochester.edu/camelot/text/collins-arthurian-court-list-in-culhwch-and-olwen tells us about Arthur's gatekeeper:

"Glewlwyd Gafaelfawr: Glewlwyd Gafaelfawr serves as Arthur's gatekeeper in Culhwch where he (in typical gatekeeper fashion) protects convention by denying Culhwch entry into Arthur's hall until Arthur requests to see him. He also accompanies Arthur in the hunt for the boar Twrch Trwyth where he loses all of his servants save Llaesgymyn.

Glewlwyd Gafaelfawr appears in Pa Gur the eleventh century text from The Black Book of Carmarthen in which he refuses Arthur and his retinue entry into a castle, thereby compelling Arthur to provide a list of his companions and their exploits. Although the poem is cut off after 90 lines it contains many of the same characters invoked in Culhwch's list and many have argued that Culhwch derives from Pa Gur. This is possible although the gatekeeper/retinue motif is relatively common in Celtic literature (cf. The Battle of Mag Tuired from the Ulster cycle and Preiddeu Annwn.

Glewlwyd appears also in the Triads (88) as one of the "Three Irresistible Knights" of Arthur's court, and in the Gereint where he serves once again as Arthur's gatekeeper—an office which, according to this text, he fills only during three festivals per year. Not surprisingly, Glewlwyd functions similarly in Owein: Chwedl Iarlles y Ffynnon (Owein: the Tale of The Countess at the Fountain) where he is the gatekeeper at Arthur's court in Caerleon. Here, his role as an upholder of courtly convention remains, although he is not portrayed in opposition to the heroes entrance to the fort as he was in both Pa Gur and Culhwch. The text reads: "Glewlwyd Strong Grip was there acting as gatekeeper, greeting guests and foreigners, beginning to honor them, telling them habits and customs of the court, and informing those who had a right to go to the hall or the chamber, or who merited lodging" (Gantz, p. 193)."

The idea for 'Doorkeeper' or 'Gatekeeper' for the name of the fort may have come about, ultimately, from the constructed form of the fortification.  Here is the plan from Radford, C.A.R., 1951. Report on the Excavations at Castle Dore. Journal of the Royal Institution of Cornwall (ns), 1, pp.1-119, showing the specially designed inturned gate:

Note that near Castle Dore is a Treverbyn, that is the 'Settlement of Erbin.'  Erbin was the name of the father of Geraint (or son in the Life of Cybi).  

I feel fairly confident about this etymology.  If it is correct, I would propose that the original name of Castle Dore was Caer Gwrlais.  As Geoffrey of Monmouth created his separate charactere Gorlois from the gorlassar epithet Uther gives himself in the MARWNAT VTHYR PEN, we can state authoritatively that if Castle Dore is, in fact, Caer Gwrlais, then it is also the fort of Uther.  

In https://mistshadows.blogspot.com/2021/10/the-forts-or-settlements-of-gorlois.html, I demonstrated that another Gwrlais/Gorlois place-name is in the midst of several Geraint place-names, and is especially close to Dingerein, the Fort of Geraint.  I believe this lends support to the notion that Uther Pendragon is a Welsh folk attempt at the magister utriusque militiae rank belonging to the early fifth century Gerontius, general of the Western Roman Empire.  This particular Gerontius was conflated with a later namesake, Arthur's father.