There you are! I told you King Arthur used to party in Kellybray. If it's in the Mabinogion it must be true!
I doubt if Gunnislake was where he (the deserter -- not K.Arthur) lived. As I was told the story in 1960, he was captured somewhere in, or close to, Callington itself. As the truck carrying him and his escort approached the bridge at Gunnislake, he escaped into the woods. When I was there the road was heavily wooded on both sides. Apparently, he went up from the road, through the trees until he was cornered somewhere above and dived into the river.
Best of luck.