Thanks but the program already exists and it's in Perl:

$ head -n 4 `which rename`
#!/usr/bin/perl -w
#
#  This script was developed by Robin Barker (Robin.Barker@npl.co.uk),
#  from Larry Wall's original script eg/rename from the perl source.
[download]

I just need a new improved expression that catches all stupid file names and converts them to something sensible. The original post does it ok, I'd hoped someone had a thoroughly tested expression ready to post.