steve I have exactly the same problem on my 3dr. I'm no expert on the wiring in the car, but I found the boot light to be operated by a tilt type switch found inside the boot near the lock solenoid mechanism. It's a bit tight to get to but can be reached.

Sadly mine seemed to work ok but the light was still permanently on so in the end I just took the plug off the back of the light and it seemed to cure the alarm problem. LOL