Oooh! I just got back from Shrewsbury Festival and saw lots of things that are right up your street, Nick.
If you want real old traditional English stuff - go back to the last of the originals - The Copper Family, Harry Cox, Sam Larner, The Watersons, and so many more.
Check out Topic Records, they do loads of stuff. Also Sanctuary records put out a lot of stuff. They took over a label, but I can't remember which one right now.
There is a 20 disc set, the name of which escapes me right now. I'll post it here when I remember what it's called.
Alternatively, come round my house and take a look at what's on my CD shelves. I've got plenty here you might be interested in.