The first thing to check is the harness as it enters the boot, they are very prone to wear and as the cable that feeds your lamp is giving a double live feeds through there I wouldn't be surprized if you found your problem there, be carefull when inspecting so as not to cause more damage. The look is to be found at the left hand corner when you open the boot, peel back the cover till you find the wires you discribed and check them out.

Good luck now

Harry.

By the way, I had the same problem, and even I fixed it

 

Tracing wires, the only conclusion I can come to is that the switch is in the lock mechanism - seems odd I know, but can someone confirm that for me?

Yes, the switch is in the lock mech. use a screwdriver to "lock" the boot and the light (well, not yours.. ) will turn of.

Best of luck, try Harrys advice.

 

This link is for a 200 , 25

But sure very similar for your car

http://forums.mg-rover.org/showthread.php?t=269475&highlight=boot+light

 

Excellent thanks, the link showing how the switch in the lock mechanism is very useful.

Did suspect the wiring loom on the hinge as I've seen lots of posts about it. Had a quick look, and someone has already been in there because the plastic tubing has been neatly split down its length. Didn't have time to delve deeper though.

Does the same switch activate the alarm as well, or does it work off a voltage drop? I think that the alarm doesn't go off when the boot is opened and the doors are locked. I say only think, because I've never tried it on purpose. Were all F's fitted with an alarm?