Pseudonymous wrote -
Pardon says he did learn some 'folk songs' at school, but plainly differentiates between what he learned at school and the 'old' songs he learned from Billy.

I found this to be quite a common experience when we used to book the old singers in Sussex at our club in Lewes, particularly for our 'Sussex Singers Nights' when the entire evening was given over to them. Every time George Spicer came - and like most of them, he didn't wait to be booked to show up, he came because he enjoyed the evenings - he would say "I don't know any folk songs, you know!" and then he would disprove this by singing them in an absorbing and entertaining way.
There was also some mutterings about where Bob Blake and Bob Lewis learned their songs.... but it didn't actually matter that much. They were all good singers, they had that authentic style of the pre-folk revival singers and those who came learned a lot from them.
That was all that mattered.