Some further progress.
The handle thing is a bit of a red herring in this case.
There are a couple of connections for the handle buttons to the Keyless Control Module but these are just passive, don't affect the Keyless module being on the CAN bus.
So I had 2 modules, one worked in the right side and one did not.
None of the the 2 modules worked in the left side at all.
After a lot of prodding and poking I found that that the CAN signal was not getting to the left module.
Much much much more prodding and poking and found:
This is the CAN bus link (brown/black) to the left rear door so will be why we can never see the left Keyless module.
The wire is broke, you can see it curled at the top and the other end behind the brown wire.
Stripped the loom back and carried out a repair checking the various wires along the way.
The one known working Keyless module now works in either the left or right rear door.
No luck with the other module, does not work at all in any door.
So looks like a combination of two faults:
1. Drivers side (right) Keyless module faulty.
2. Passenger side (left) wiring harness broke.
Just need another module now to confirm then can rebuild everything back up.