Here's another tantalizing quote from a novel: Where the Land and Water Meet by Julian Moynahan (New York: Morrow, 1979):

Ace went to the window. He put his head out and sang melodiously, "Does Your Mother Come from Novy? Did she get here in a dory?" Then he said, in a fake English accent of the lah-di-da variety, "I say, Rory, er-ah get your er-ah dory, because er-ah I do believe there er-ah is an er-ah herring in the er-ah bay." He went from there into fake darky lingo....