Rod Stradling's MT Records CDs of "source singers" have been a bit of a revelation for me. You can get the sampler for a tenner, and it's well over an hour long. Be warned, though -- if you get the bug, you'll end up buying a lot more.

The version of "The trees they do grow high" on Walter Pardon's "A world without horses" (Topic) completely changed the way I think about (and perform) that song. He's probably the traditional singer that I love the most (rather than admire).