Emma Miramax

I have a question about the music in the movie Emma by Miramax. I have the soundtrack and love it, but finds it lacks one song I so dearly wish to own. I am not positive on the name, but the song I speak of is the one Emma and Frank sing on the piano forte. They sing a duet I know it starts out "Did you hear my lady, go down the garden singing". Does anyone know the title, who wrote it, but most of all where can I get it? Is there a CD in circulation that I could purchase? Thank you for your time, KED