It is probable that the Damnoni of Strathclyde believed in the same myths and legends as the other Celtic tribes. Part of the Irish myths seem to originate in Strathclyde; one of the greatest heroes of the Ultonian cycle can be traced to British origin:- Cuchulain, the warrior hero of King Conor mac Nessa, is most likely British.
In the Irish legend, Cuchulain was conceived in the Fairy Mound of Angus, on the river Boyne. The true origin of Cuchulain, however, is revealed by his original name; Setanta. Ptolemy places the Setantii tribe in the Ribble Valley and hence the inference that Cuchulain is British.
The Irish legends do hint at the British origin of this warrior hero. There is a battle Cuchulain fights with Ferdia, a Damnonian. Cuchulain tells Ferdia that he is unwilling to fight Ferdia, as they are friends and of the same race.
The Celts also believed in similar gods. Epona was the goddess of horses, no doubt venerated by the neighbouring tribe Epiddi as well as the Damnoni. It may be that this was the derivation of Drumchapel or drum chopuill. As cattle were of such importance to the people of Drumchapel, the goddess Damona (c.f. gaelic damh, ox) would be venerated here. The goddess Nemetona would also be worshipped, the originator of the race. Many of these gods though would be modified or replaced by the coming of the Romans and later Christianity.
I.M.M. MacPhail notes that Dumbarton was connected with Fingal, in James MacPherson's Ossian - a work which has since been widely discredited as a forgery - where Fingal laments "I have seen the walls of Balclutha but they were desolate.. The thistle shook its lonely head; the moss whistled to the wind." In his Dumbarton Castle, MacPhail writes "Celtic scholars since his time have been able to show that there existed a considerable corpus of Ossianic or ancient Gaelic poems, which had been preserved by oral tradition through the centuries, but none has been found which could be connected with Dumbarton Rock". This lack of oral tradition in the Drumchapel area is puzzling, but it may be explained by the close proximity of the Picts and much later the Scots of Dalriada; the Lennox may have been a melting pot of Celtic legends. These legends will be discussed in a later chapter detailing the Kingdom of Strathclyde, but this melting pot idea is noted in Stuart McHardy's The Quest for Arthur: "The P-Celtic speaking peoples of Strathearn and the Lennox in west central Scotland lived close to the lands of Q-Celtic speakers in Dalriada and they obviously could, and did, co-operate when it was seen to be to their mutual advantage." This co-operation, I contend, resulted in a short-lived High Kingship or Ard Righ also discussed later. McHardy goes on to note: "The nineteenth century historian W.F. Skene, who was extremely interested in matters Arthurian, went so far as to suggest that the stories of Arthur amongst the Britons and the story of Finn MacCoul among the Gaels might have originated in the area where these two different groups lived alongside each other, and thus might have a common root."