Today I had to replace a Triton Ivory II shower and found that the Madrid II was a straight swap ... maybe the info will be of use to someone. Argos had the best price I could find for the Madrid II.
A word of warning about the Ivory II - the internal connections are all push-on and a couple of years ago the damn thing nearly caught fire because of the contact resistance. The Madrid has screwed connections so I presume they had a lot of failures and changed the name when they dropped the push-ons.
Dave