I'm having problems with the tailgate on my MK1 estate in that it will open of it's own accord. I can leave it overnight and it won't open,but more often than not when I start her up,the tailgate will open. I don't mean open fully but just unlocks and once moving will rattle and of course the 'door open' light comes on. The car doesn't have to move anywhere,just sitting on the drive with the engine running will do it. Water ingress?. Fob problem?.

I've just been out to try and replicate the problem,but of course it won't do it now. Perhaps I was inadvertently pressing the ' unlock tailgate' button on the key when I was starting it. Doh!.

bet its water happens a lot

Check the wiring in the rubber conduit between the roof and boot lid.

The insulation gets brittle and snaps the copper core resulting in a short circuit.

I'd do it asap as it will blow the boot lock solenoid quite quickly.