Stopped working on my 53 reg Astra convertible around 6 months ago but since the only thing thats ever in the boot is a pair of 12" subs and an amp i wasnt in any particular rush to fix it. Anyway the weather today was alright for a change i had the chance to get a whole list of things sorted that i'd been putting off and when i finally finished those i decided to take a look to see if i could solve this little issue, heres what i found ...
Behind the trim on the nearside of the boot just above the boot light, No idea why because it isnt touching anything but 3 wires were completely broke and another 3 were split exposing the core. Was just a case of reconencting all the wires then covering with tape to stop it happening again. Central locking is now back to full working order once more. Only thing i will add is 2 of the wires that go into the plug are the same colour, you'll have to check when reconnecting because if you do it backwards the brakelight on the tailgate flashes when you lock the car.
For those who just prefer pictures -
Hope this is of some help to others with a similar problem.