John C - if I hadn't seen anything other than the Penguin Book of English Folk Songs (or Classic Folk Songs as it now is) I might agree with your suggestion. Yes it is a classic collection, and now with additional information about the singers who sang the songs, and the verses that Vaughan Williams and Lloyd left out or tinkered with - maybe guest Ben should consider getting a copy to start himself off with. I've owned most editions of it,adn return to it frequently, but then I moved outside it's contents and found versions that I prefer/ other types of song which it does not touch. After all, it was in itself a selection suggested by only two individuals.
Frankly I don't think you CAN make a list of only 10 best songs - everybody's taste differs, as does their experience of folk songs. The regional difference in types of song sung in clubs is quite marked even on a local basis for starters. However, it's certainly fun trying, and seeing what others suggest.