As the alarm has never worked, I doubt it would be that. Do leave it unlocked in the Garage though. Given that my fans, er the cars not mine as I'm not famous, are quite noisy even on low speed, I'd hear if they were on all the time.
Will try locking it and see if it makes a difference. Is there a way to check with just a basic analogue multimeter, any other sources that could be causing it to drain. don't really want to keep disconnecting the battery to keep it charged as then I have to go through the re-learning process for the ECU every time before I drive it. Occasionally twice when it wont rev cleanly whilst driving.
Thanks all for the suggestions.
PS: What did you think of the Great Ocean Road when you were in OZ Dave?