I saw this thread yesterday and went into the link which shows you the photos and the estate agent leaflet, where you can see the 'layout' of the house. Looking at it, it was obvious that the room shown in the photo as 'Tolkien's Study' is the largest of all the reception rooms, now the drawing room (or 'front room' to those of us Oop North).
If the photo did correctly identify Tolkien's study, then it amuses me to think that he had so many books that his wife let him have the biggest, and best room for them! Perhaps it was also a question of allowing him a room which caused little disturbance. I can just imagine him creeping in through the front door at midnight after a session in 'the bird and baby', trying to be quiet but failing (as we all know, the volume on life is turned up when we have had a drink
), and retreating into his huge den to write about Middle earth...