Campbell became involved in the folk music revival taking place in London and met Ewan MacColl, who was an influential figure in the folk movement. However, the two men disagreed on their approaches to folk music, with MacColl taking a very purist view that people should only sing music from their own regional background, whereas Campbell had an eclectic repertoire and sang whatever he liked, whether it was a Scottish Ballad, an English folksong or an American work song. A contemporary article in "The Observer" attempted to characterise the folk community into two camps: the "MacCollites" and the "Campbellites".