Mike, my point was not about whether "You'll never walk alone" is a folk song, but about different uses of the word "traditional". In the context of folk music it has a certain meaning, but in general usage its meaning is wider, and it may be "traditional" to perform pieces of music which are not traditional in the folk sense, either by origin or in style.

Bert Lloyd's comment about "folk in function but not form" says it far better than I did.