Jim as far as I am concerned a traditional singer,is someone who has learnt his songs orally from his family or from his local environment.
If Walter Pardons family repertoire died out between the wars,and his repertoire was reconstructed painstakingly by Walter,[your words],he had to revive the songs,in the strict meaning of the words Walter was a Revivalist,his family songs had died out and he had to revive them.
To my way of thinking a traditional singer is someone who doesnt have to consciously revive a song.
I think what is more important is the calibre of the singer,Walter was a good singer ,so was Bob Blake,and here I would like to quote MikeYates[talking about Bob Blake]

"At the end of the day it doesn't really matter whether or not Bob Blake was a 'traditional singer'. Bob, I'm sure, was true to himself, and if a young, inexperienced song collector (i.e. me) was willing to impute a label onto Bob that, with hindsight, was probably inaccurate, then the egg is surely on my face! What really matters is the fact that Bob was a fine singer and luckily we did manage to record him singing some of the songs that he knew. Also, many people today want a world of certainties, a world where our every thought and desire can be seen in terms of black and white. But, of course, life is not like that and, kicking against this, we so often find ourselves suffering from the unsatisfactory nature of things. Bob Blake gave pleasure to many people by singing his songs. Singers like the Coppers, Bob Lewis and George Belton became his friends and accepted him as their equal. I'm glad that I met him and heard him sing, and, at the end of the day, that's what really matters to me.

Mike Yates - 8.8.06"
The above is from musical traditions.
Malcolm Douglas,I prefer Mike Yates,s take than yours .