Complex sentence: The subject of the opera is the "Dirty Duchess", Margaret, Duchess of Argyll whose sexual exploits were the stuff of scandal and gossip in Britain in 1963.
Split into simpler sentences: The subject of the opera is the "Dirty Duchess", Margaret, Duchess of Argyll. The opera covers the life of this remarkable woman whose sexual exploits were the stuff of scandal and gossip in Britain in 1963.