Thanks for that and yes, I did know that Rolls Royce was always particularly proud of how their woods matched all over the cars. But I have checked and the replacement doesn't look too far off; also, the airbag cover has popped off at some time and that piece of wood has been replaced with quite a bad match. I might almost like to change that piece of wood itself for one that will (now) match the door capping!
The job itself doesn't look too daunting as you mention but it has enough steps to make it more appropriate to leave to an expert who will know or remember where all those bits went.
While I am in there, I wonder if it might be worthwhile upgrading the speakers (on both sides) to improve the sound? I already put in an Alpine PwE-S8 subwoofer on the rear parcel shelf to isolate the sub-frequencies and prevent them from going through the door speakers and the sound is completely transformed!