Does a simple way exist to identify the culprit door, boot (trunk) or bonnet (hood) that shows it as being open??

 

Other than the dash display saying "boot open" or "driver's front door open", etc.?

 

Dean, I take it your interior light is remaining on because the car thinks there is an open door? If so, this is no easy way to determine this other than using a multimeter at the GEM module to measure each switch contact. With that being said, you can get an electrical lubricant (WD-40 here in the states is an easy one to find) and then inside of each latch, follow the part of the latch that holds the door shut. If you look on the bottom, you should see where a small push button is. Squirt that switch with the electrical lubricant and then open/shut each door a few times. Don't be afraid to let some of the lube run out the bottom of the door. May want to even do a second trip around the car to lube the switches a second time. odds are, that will take care of your problem.

 

Mine actually says hood open, trunk open driver, front driver rear , etc ..... I figured they all did. Mine is a 02 base model.