Just to help out Pseudo. Traditional refers to an accident of birth. A singer is a Traditional singer if he or she has been born into a family who sing songs and a member of that family passes them on to you. So I learned a number of music Hall songs Traditionally. The next qualification is Folk Singer. I have met numerous Traditional Folk Singers and learned songs face to face, but it does not mean that I am one. I am a revivalist, and about as close to the tradition as any one can get without being born to it. The third unwritten qualification is style. There are Traditional singers who have lost their family style of singing, and sing with a style gleaned from country music or art music.
Walter Pardon was born to the music, had a vast repertoire and an exemplary Traditional singing style. That's why he's important.
It's as easy as that imho.