I'm perhaps being unfair, and it truly is remarkable how much of the original look you can still see, but even from the outside it is obvious where doorways and steps have vanished, windows been enlarged and modernisation taken place. This is particularly true on the side where the Bishop's Palace sits. During the refurbishments it was fascinating to see the infrastructure and where doorways have been added, removed and relocated. A prime example is the main foyer when you come into the building.
Facing you, you'll see a doorway to what is now the student reception, and a solid wall. If you knock ( gently if you please) under the large screen you'll hear a hollow sound, where the symmetrically matching second door used to be. Which was a fake door leading no-where but important for the aesthetics. The doorways you CAN see, has quite oddly been moved a few inches to the left, and then a few inches to the right over the years. The doorways to the right of this, as you face this wall, leads down steps and out to the rear yard. When originally built however, the current student reception was actually the staircase and rear exit from the building, and the doorway next to it was a solid wall hiding the china closet and safe. And if you're standing there looking through it I'd be careful, as you're standing on what used to be another staircase parallel to the wall leading down to the basement, loo and billiard room.
The miracle is that all the murals and most of the wall paneling and coving actually IS still original, and even the carved post at the base of the main staircase dates right back to the building of the house. As I said, 'Trigger's Broom'. And a rather astounding restoration job.