The music was written by Andrew Lloyd Webber, with lyrics by Don Black.

The song was released by Marti Webb and Justin Hayward as a duet in 1981.

Later, Black wrote new lyrics to the melody and retitled the song "When You Want to Fall in Love.

"[2] The original lyrics were re-instated when the show was re-written for Sarah Brightman's run.

"Unexpected Song" was later used in Lloyd Webber's and Black's reworking of the show, returning to the original album title of Tell Me on a Sunday.