I'm trying (in vain) to find some music notation software, or ABC player
for the Psion 7 but no one seems to have written one.

Does anyone know a) if such software exists, and b) if not, what is it
about the Psion 7 that stops people writing such software.

I am aware of an ABC player for the Psion 5 and 5mx, but this doesn't
work on the 7...