The "Greensleeves" is an old English song that has been around for some time.
A broadside ballad by the name "A Newe Northen Dittye of ye Ladye Greene Sleves" was registered by Richard Jones at the London Stationers' Company in September 1580.
This means that the composition is in the public domain.
The melody has also been used in a very popular earworm, "What child is this".
Although this composition is in the public domain, there is no doubt about that, quite some
music companies are trying to do copyright claims over this composition.
Now, enjoy the show, I'll do the disputes!