I purchased another Mk.IV with English as one of the languages in its firmware, so I have no direct need anymore.
Swallowed my pride and mentally "wrote off" the Euro 75 I had paid for the original Italian/French/German one (now I know why it was cheap!) and it is still sitting on my 'spares-shelf'.
I had already purchased a Resler USB interface cable to hack into the K-Bus too, but chickened out in case I really screwed things up! Also, although I downloaded Navcoder and found an English .LNG language file to download, you had said back in June '20:
... and that I did not have, so the Resler interface is also now sitting next to the Mk IV on the 'spares-shelf' !"it will ask for the firmware CD for the satnav language change, and you can't use BMW ones on a Rover unit, you need the specific Rover CD.".
David