Down by the Greenwood Side is a "dramatic pastoral" composed by Harrison Birtwistle to a text by Michael Nyman.

It was first performed on 8 May 1969 at the Festival Pavilion, West Pier, Brighton.

[1] The New York Philharmonic staged the opera as part of their New Horizons music festival in 1984 with conductor Larry Newland leading singers Susan Belling, Bruce Vernon Bradley, Richard Levine, John Lankston and James Billings.

The soprano, Mrs. Green, sings the ballad while the actors and mime perform the play.

But near the end, in the final tableau, there is a slight acknowledgement of each other's worlds when the presenter of the mummers' play, Father Christmas, completes the story Mrs. Green has been telling, and Mrs. Green momentarily enters the mummers’ acting area.