No one has mentioned Richard Thompson, yet. Or Martin Simpson. Bert Lloyd ? Chris Coe ? I love the singing of all of these and have no problem in thinking of them as great - and influential - singers. However, when I play their work to people unfamiliar with folk music their initial reaction is frequently negative; often with classical or classically trained ears used to a heavy vibrato. The same thing happens with 'violin' players listening to 'folk fiddlers' - after a while the penny drops.