Most of the WSD fans know that the original film was to have three songs in it, all written by Mike Batt:
Losing Your Way in the Rain - performed by Art Garfunkel (during the rain scene before Cowslip's appearance)
Bright Eyes - performed by Art Garfunkel (during Hazel's death)
Run Like the Wind - performed by Barbara Dickson (during the running sequence with the dog)
Of these, only Bright Eyes survived, and barely at that. Losing Your Way, while not featured in the film, has appeared on the tv soundtrack album. This song fits the film perfectly lyrically, though I'm not positive if Garfukel's voice would have worked so well at this point in the film. It was airy and dreamy for Bright Eyes, which was perfect considering Fiver was following death around the down.

Very little is mentioned about the third song, meant for Hyzenthlay as she leads the dog to the down's crest. It hasn't been featured on any WSD merchandise or either cd album. Besides the intended original performer, others have covered the song. Lyrically, the song should fit, but when hearing Dickson's version, part of me is kind of glad it didn't make the film. Angela Morley's score at the dog chases the rabbits is far more enthralling than any pop song could be at that moment in the story. Its nice, but it wasn't necessary to make a good film better.
Without further adieu, WSD's lost song:
http://www.youtube.com/watch?v=Z3EPoXkd3oI