The Gloss instrumentals are all based in the key of F sharp major (or E flat minor) because this is a really easy key for piano improvisations, though a bit of a bitch on the guitar. This particular one has the note of G thrown into the mix as well.
This track exists in several forms with various cubase lead guitar resyncings (oh oh, I'm getting a syncing feeling about this). This version (I think) is the largely unresynced version 1 lead guitar take with the end of the first solo cut cos it had too many bum notes.