Its a Connects2 adaptor ADP044 or ARVS005MK2 which is no longer made as Connects2 are no longer supporting MG/Rover range and are withdrawing as stock sold.
One I have here is beyond repair I'm afraid.
This one is for a Sony CD/MD/MP3 adaptor.
"My lovely car now sold onto a very happy new owner.
I still love this marque and I will still be around, preferred selling to breaking, as a great runner and performer"