St Mungo … was even supposed to be related to King Arthur, apparently being his great-nephew.
According to Jocelin of Furness, Tenew had an affair (he says with her cousin, Owain). When her father found that she was pregnant, he was obliged to follow the law of the times, which was that sex outside marriage was a capital offence, and kill her. (Jocelin says that Loth was pagan. But all the Arthur stories point to Loth being Christian). He decided to throw her off Traprain Law, a large hill outside Edinburgh and which at the time was still used a fortified settlement. However, she survived the fall. That apparently was not enough for Loth or his subjects, who were in two minds as to whether she might be a witch (emphasis mine).…
…There, on the beach, she gave birth to Mungo, or Kentigern as his proper name is. (Mungo is the nickname given by St Serf, but there is debate as to what it means. Some say “My Hound”, others “my dear heart”. Kentigern means “Chief Lord”.) …
The story is almost certainly some sort of gloss on the fact that Mungo was illegitimate.
The next point in the story is Mungo’s election as a bishop. …
He went south, first into the southern part of Rheged, into what is now Cumbria, where there are many churches dedicated to him, and then to what is now Wales. …
…this makes Mungo founder of Glasgow. When Mungo died, he was buried in his own community, making the site one of pilgrimage and importance. Around it arose a township, and by the 12th century it was a cathedral city.
…The city’s coat of arms, which was the same as that of the old pre-reformation diocese (for the simple reason that the bishop was the civil power in the city until the 17th century), shows the saint at the top and … contains elements linked directly to Mungo. There is his bell. The bird and the salmon with a ring refer to two of his miracles. The bird, a robin, had been a pet of St Serf, but some fellow classmates, jealous of Mungo, killed it, hoping to pin the blame on him. Mungo restored it to life.
The salmon and the ring relat to Queen Longuoreth’s adultery with a young soldier and Mungo’s saving of the Queen. …
In prison, she sends a messenger to Mungo asking for forgiveness and aid. When the messenger arrives, he is immediately told by the bishop to go fishing in the Clyde and to bring back straightway the first fish he catches. This is a salmon, which, on being cut open, is seen to contain the ring. …
Exactly what gave Mungo his reputation will not be known this side of the grave. Suffice it to say that there was clearly something in the man - maybe it was great holiness - that made the memory of him endure through the centuries. …
He died on 13th January, 613, and there is a final interesting point in Jocelin’s Life. Jocelin admits that he used earlier written sources but that he edited them because he found some of the stories incomprehensible. He tells us however, that on the Octave of the Feast of the Epiphany (13th January), Mungo entered a vessel filled with warm water and then, encircled by his brethren, “yielded up his spirit”. It has been suggested that Jocelin was unaware that he was distorting a more credible story involving an a mass Epiphany baptism. The suggestion is that at Epiphany Mungo conducted such a baptism, which at the time was still done by complete immersion. In early January it is still rather cold in Glasgow, and even today it is customary in the locality to warm up water for baptism. The thesis is that Mungo went into warmed up water to administer baptism but then caught a cold and died a week later. The date of his death is kept as his feast day.