I don't suppose it's the first time classical music has been played in a folk club. E.g. where does 'Early Music' fit in.

I was calling a wedding ceildh at a hotel in LLangollen and a Male voice choir were staying an extra night because they'd won their class in the Eistedford so sang in the evening, which they also won. They came and sang for the wedding guests - a folk song arrangement which sounded incongruous to my ears.

But I would suspect that settings by Vaughan Williams might be more sympathetic.