I have just read through this thread, and have really enjoyed it all.

I have used the Baring Gould Book "Songs of the West" - and another book given to me by Jack Spurr, a Cornishman from Calstock way, "Cornish Ditties" I think it was called - for years, and based many of the songs on my CD "Best of Cornish Folksongs" from material in that book. Like Phil Beer I have used song books like that to sing from, since childhood. In my childhood it was family gatherings on a Friday night, and always with guitars, whistles and lots of humour (I was born in 1953 too Phil!)- in my native county of Essex.

Arscot of Tetcott was a song I found in "The Songs of the West", and which I also recorded and put on CD in the early 90s. So I did it a while before Jim C. (but a very modern take on it - not very folkie)

Another source for me was the singing of the Male Voice Choirs. Those lads are a mine of information on all songs Cornish.
I loved my time living in Cornwall (from 1978 until 1996) and am still trying to escape Devon and get back!