The music for 'Roses', and the other songs in the play 'Red Roses for Me', was set down by Brigid Edwards (1888-1977), a music teacher at Dartington Hall: the progressive school in Devon attended by O'Casey's children. I suspect that she didn't actually compose the tune. O'Casey had a wealth of traditional melodies in his head and probably just employed Brigid Edwards to write out the notation.

I always felt that the song was a bit too short - and therefore wrote two additional verses of my own! I can't find them at present (!) but if I do I'll post them.