"When Martin Carthy collected 'Rose OF Allendale' from the Coppers , it was a Folk Song - Now that we know it was an early Victorian parlour song , does that stop it being a Folk Song ?"

Funnily enough I was thinking something along those line about Blue Murder's recording of the gospel song No One Stands Alone by Jimmie Davis. Does This make the song a folk song or does it make Blue Murder a gospel as opposed to a folk ensemble?