According to the Internet source given below, Flanders and Swann were a British comedy duo. Lyricist, actor and singer Michael Flanders (1922-1975) and composer and pianist Donald Swann (1923-1994) collaborated in writing and performing comic songs. They first worked together in a school revue in 1939 and eventually wrote more than 100 comic songs together.
Between 1956 and 1967, Flanders and Swann performed their songs, interspersed with comic monologues, in their long-running two-man revues At the Drop of a Hat and At the Drop of Another Hat, which they toured in Britain and abroad. Both revues were recorded in concert, and the duo also made several studio recordings.

Websites:
	Flanders and Swann	Biography by wikipedia.org.
	Flanders & Swann Online	Performers' home page.