This is the only photo I've come across so far showing a part of the school that doesn't exist any more: the gym/chapel on the right and the cuboid block on the left, with classrooms on the ground floor and New dorm above.
The bell above the door was the main school bell but I don't remember exactly on which occasions it was rung. Entering through the door, I remember a long corridor running up to the tuck shop at the far end, with classrooms on the right and then a dining room further on. I don't remember what was on the left, apart from the entrance to the large changing room with communal shower. I have a feeling there were some offices on the left near the entrance.
It would be quite interesting to get hold of a complete floor plan of the school as it used to be.