Having completed the essential work on my multijet dynamic, I have turned my attention to the common tailgate microswitch problem. When I removed the trim I noticed that the electrical connection to the lock was disconnected. There is obviously a hidden power connection on the other side of the lock as I have remote unlocking and the handle works when the microswitch is not playing up. There is no indication of tailgate open on the dashboard like a door not properly shut. I have owned the car since it was two years old, long before the microswitch started playing up and have no reason to believe that the trim has ever been removed before.

I find that when the switch is stuck that if you press gently on the black plastic at the other side, it'll release it.

I've completed the microswitch job and I tried connecting the electrical connection, everything works as before except the door open warning on the dash stays on. I have disconnected the plug from the lock mechanism before fitting the trim.