Thanks everyone, with your help I was able to fix the issue.
I removed the rear wheelarch liner, plastic protector for driveshaft and rubber insulator that the inner tie-rod passes through. Removed the tie-rod assembly again and steered left to send the rack-bar out of the rack.
I then cleaned it really well and applied liberally Millers DELTA 3EP as this seemed most like the original (The BMW stuff was very soft yellow grease)
Here are the photos but they are all rotated 90˚ CCW (why does this happen on this forum, I have also resaved and reuploaded them with the same result?), you can see the spanner on the nut on the 'movie'. The nut turned easily and in a few increments with test drives, I did it a full turn when the rack was dry and then greased it up once satisfied - there is no binding off-centre, in fact it feels no different than before. One day I will do the plain bar on the passenger side just to protect it.
Attachment 22231
Attachment 22232
Attachment 22233
Attachment 22234
Attachment 22235
Attachment 22236