I would certainly not be so rash as to claim that traditional sides only ever danced to a solo musician. Anyone seeking 'strict authenticity' in these things is on shaky ground. And it is undoubtedly true that a far wider range of instruments were formerly used than would now be considered to be "folk" instruments.

However I do stand by my view that in Cotswold morris the subtle interplay between music and dancers is often one of the features which distinguishes outstanding sides from the run-of-the mill, and that this can be best achieved with a solo musician. No doubt someone will now point out morris bands who can achieve this, but I think they would be exceptional.