I have been slowly going through everything on my car fixing stuff and not really needed to ask too many questions but this one I may need a bit of help pin pointing the issue. I was having a problem with the central locking but thought I'd get one job out of the way at a time. This is also a bit of a how to guide also for anyone who's not gone through the door handle re-fit pain yet.
I started off by trying to find out why my passenger side door lock was seized and after removing the door handle and stripping the barrel down it was just due to the old grease hardening as the passenger lock hardly ever gets used in it life.
You can see how crudded up the externals were.

And barrel stripped for cleaning, internals were just as bad.

With this all cleaned up and working with the keys as it should.

unfortunately when I was re-installing I broke the awkward handle arm going into the door as I was twisting the handle, so I stopped what I was doing and ordered a new arm from OPC along with two white plastic actuator arms, as I already suspected them causing central locking issues.

The parts all arrived today so I got on with re-fitting the handle, again it was a PITA but eventually I got it in there by undoing the side latch first so I could raise it up inside the door before fitting the ball socket first and then the arm and pin to the exterior handle, this way worked a treat and I've never seen anyone document it this way before, recommended as it only took a few minute to fit once I'd thought of it.
Internal latch pushed up inside,

to reveal the ball socket

then fitted the arm and pin to the exterior handle before slotting it back in, not forgetting the other plastic arm.

After this success I moved onto fitting the new actuator rods in both doors, this was very easy to do, so once fitted I closed the doors and tried the central locking.
Passenger side first and on the key, I can now lock and unlock both doors.
Moving onto the drivers side I can unlock and lock the drivers door but it will only unlock the passenger side from the drivers door. I can see the actuator unlocking the door but it doesn't move when I try to lock it.
Two things I'm thinking it may be;
The actuator on the passenger side isn't working to lock the passenger door and only locks when I use the key in the door on that side because the key is locking it?
Or the microswitch on the drivers door handle isn't sending the signal to the passenger side to lock the door?
My question, is there anyone that's had a similar issue and may know a quick fix, especially if it's none of the above?