s type boot warning light

Hi all ,I have a 54 plate jag s type 2.5 with a mere 36 k miles genuine,yesterday the alarm started going off for no apparent reason as the car, although locked had opened ,I reset the alarm and walked 

away within a minute the alarm started again,i checked the car over no obvious apparent faults to be found ,this morning I used the car started her up ,and then noticed the boot open warning was on the dash together with a red light, I opened the boot ,removed the panel covering the locks and latch etc ,removed the switch  and tested it all good ,tested the latching mechanism and all working well except for the interior light in the boot  being on constantly ,operated the switch but the light stays on ,I have exchanged the latch  etc etc but the interior light in the boot will not go out ??? im at a loss to know what to check next  any advise would be appreciated  rgds tim