Who was Martha?
A coded message to Jane Asher? Or a piano exercise about a sheepdog?

When I taught myself piano I liked to see how far I could go, and this started life almost as a piece you’d learn as a piano lesson. It’s quite hard for me to play, it’s a two-handed thing, like a little set piece. In fact I remember one or two people being surprised that I’d played it because it’s slightly above my level or competence really, but I wrote it as that…