Problem Solved !
New Valeo starter motor fitted to the vehicle, and when diagnosing 'clunk' when turning off the ignition, traced the issue to the power isolation solenoid that allows power from the battery to the rear 'Anderson' plug ! The actual issue was ... when turning off the ignition, there was a small 'back flow' of 12v FROM the isolation solenoid 'engage' side that is hard wired into the 'Ignition On'. So replaced the isolation solenoid AND put a diode on the supply side FROM the 'Ignition On' to prevent ANY 'back flow' of 12v ever again !
This was the last big job needed doing on the WH to make it serviceable & reliable again !
Has been a big few weeks though changing out the following:
Front Struts x2
Both front lower control arms
Both CV's on the front drive shaft
Front sway bar bushes x 2
1x front outer CV boot & clamps
Rear shock absorbers x2
Full wheel alignment
Heading back off to work soon ... for a REST !