wav,
you are correct to a certain extent,but you seem to have forgotten about English troubadours,who sang traditional material with accompaniment
,BUT,why should we exclude accompaniment,those that wish to sing unaccompanied do it, not because its English but because its how they like to sing.
if I searched hard enough,I am sure I could find English traditional singers ,or singers of English Traditional song who used accompaniment 100 years ago
[lets see we are talking about 1909 ]Cecil Sharp didnt have a problem with songs being accompanied,in fact he wrote piano accompaniments.
are you suggesting Sharp was wrong,to use accompaniment.