my point is that Bellamy had many influences on his singing,apart from English traditional singing, he also sang blues as away of expressing himself., but decided not to do it generally speaking on gigs. Why?
I am not sure of the relevance of your remark about him spending time in your house, I am not sure what you are getting upset about has anyone suggested that he was not a friend of yours whats the problem, when Bellamy wrote sang he had many influences, however when he wrote he deliberately wrote in a certain style.
I believe   Peter knew the market he was writing for so restricted his melodies to those that were in the three most common modes found in uk and irish traditional songs, for example fiddlers hill is the same melody as when a mans in love. Peter borrowed a tune from the irish tradition to use for a song about east anglia , he did not write it in a 12 bar blues format, because he knew that was not acceptable for his market. but that does not mean that his singing was not a result of broader influences.