Flanagan was a great admirer of
Maurice Ravel,
David Diamond, and
Aaron Copland, who became something of a mentor to Flanagan. His best work was in the realm of vocal music. Although little known today, as well as unsuccessful and undervalued in his time, a number of his brief vocal compositions, including
Horror Movie and
The Upside-Down Man, have been recorded. He is best known today as having been the long-time lover of playwright
Edward Albee, with whom he wrote an opera after
Bartleby, the Scrivener. He composed music for the 1960 premiere of Albee's play
The Sandbox as well as Albee's adaptations
The Ballad of the Sad Cafe (1963 from the
Carson McCullers and
Malcolm (1966, from the
James Purdy novel). In 1963, Albee wrote one act of
The Ice Age, a libretto for Flanagan, but the opera was never completed. Flanagan committed suicide in 1969, at age 46, after which Copland eulogized him in a memorial concert given by Albee and
Ned Rorem. == Musical style ==