Retest went well. Paperwork all away.
And I treated myself to my first "private" plate.
Couldn't get R75 LHD without dvla releasing it to an auction and estimated price was over £1000.
This cost me £163 which I'm happy with. Plate itself was only £39, then the dvla £80 transfer, sadly then it was another £44 due to the car not being taxed in the UK long term.
And obviously, R40 being the internal rover design code for the 75 and is on all official parts in some form, and lhd is left hand drive.