Not sure about the seating. Of course not all Cathedral were designed with seating for all. The Hoi Polloi were required to stand. There is a time line on the Cathedral web site that has the following entry:
"The Misericords are installed
Also known as ‘Mercy Seats’, the Misericords were designed to aid the old and frail by making it appear as though they were standing when in fact they were sat down rested during a service. They are dated between 1365 and 1370."
That suggests that seating wasn't initially included in the form of traditional pews etc. There is nothing to suggest it was added later.
Denis, nothing special in the way of PP. I merely made an elliptical selection in Photoshop using the Marquee tool, inverted it to select the outside bit and then reduced the saturation to near mono. To ensure a nice smooth transition, the Marquee ellipse needs to be set for a feather of about 100 or so pixels. I'm sure that the same can be achieved in Lightroom.