Ok - had a look, and  managed to get the trim off - 1 phillips, & another 2
under the red fluorescent tabs at the bottom corners.

Boot now open, and can't really access the locking section.  It seems to be
held on with 2 allen bolts on the outside (near the number plate lights),
and not wanting to break the seal, so left it.

Put a good drop of 151 oil in the handle bit, and the boot now opens and
closes.  Left boot lid up to let the oil soak in around the mechanism.

Hope it lasts.

Graham

Had a similar problem except worse. The lock may have been forced by
someone. Inside the tailgate there are 2 rods connecting the locks at either
side to the release 'paddle' via a lever. The paddle jumped over the lever
jamming the system. I had no choice but to unscrew both locks with a very
slim size 10 spanner. You can just access the bolts through the gap between
the tailgate and the body. Afterwards I completely dismantled the tailgate
finding a lot of grime and corrosion in the release mech. Cleaned all up and
used a special water proof grease to lubricate everything. Even took apart
the rear wiper as its shaft was starting to seize due to corrosion.

Mine does exactly the same.

This is what you need to do...

Unlock the central locking. Get some long nosed pliers or a bent bit
of wire and pull the handle out.

Lock the car, then unlock it again.

You should now be able to open the boot.

To get at the lock mechanism, you can remove the insite panel from
inside the boot. This will allow you to get at the handle mechanism.
There are more than the one you have seen - have a look round the
edges, I can't remember where they are exactly.

I think this is what I will be doing this weekend in my Weekend.