1 - The south-eastern block
A fireman walks along the front of the school, past what were once RE and Classics rooms. This is where the Geography and History rooms now stand. To the right, the south-east entrance is burning to the ground, and the windowframes of the classroom / corridor wall are lined with flames.
2 - Flaming windows
A dramatic shot of what I presume is the south-eastern front burning away. If that's the case, it looks like this was taken before the previous shot.
3 - The south-eastern facade burns away
The south-east entrance is the flaming box that protrudes on the right of shot, while the main entrance is just off the left of shot.
4 - Looking west through a window at the south east entrance
This is the same wing as the above shots, taken the morning after, and at 90°. The nearest rooms are Classics, and beyond that are the RE rooms. The western side of the main entrance is still standing, opposite the trees at the lower school drive. The row of chimney-like things that run through the smudgy negative-print at the right of shot are the classroom / corridor walls; the gaps previously housing those flaming windows. Not sure what went at the tops though. Through the gaps can be made out the corridor / quad wall.
5 - The main entrance
The railings at the right guard the sheer drop to the crypt. At the back they come to a dead end where the exterior wall used to be (the masonry can be seen going half-way up, with a pitched concrete top). To the left, a hosepipe lays along the ground, trickling in water. The arched window to the left of shot seems to sit between the corridor and the main hall (although photo 18 suggests otherwise); the main hall marks the approximate location of the fireman (centre-left). The burnt out spidery mess above him was once the main hall roof. The wall at the back is the fireplace thing which we'll see in greater detail later.
6 - Main entrance, looking along the south-west facade
A shot to the immediate left of the previous photo (note the hosepipe in the bottom right), looking into the shell of the east-most language lab. This is the part of lower-school that can be made out in the distance of photo 2.
The railings here are the ones opposite those depicted above, and border the entrance to the crypt (access to which is between the window and the bin). It was a bin such as the one centrestage inwhich the fire was started (see later). The burnt down part of the building here was one of the deputy head offices. The arched window to the main hall can be seen again here, to the top right of the circle-device in the railings. To the left of that, behind that monolith of still-standing building in the centre-ground, is the doorway to the main hall.
7 - The fire-escape of the east-most language labs
Mr Kirkpatrick and a woman (perhaps Mrs Cooke) drag out a cabinet (with a record-player on top) from the fire-escape of the two eastmost language labs. The protruding classroom to the right is the gutted room from the last photo, seen here from the other side. The adjacent, recessed room is the one Mr KP has just exited, and appears to be relatively unscathed (a display on one of the windows of the far wall can just be discerned through the left window, still in place). 
The fire-ramps were new additions to the building, following the admission of a girl in a wheel-chair.
8 - The south-western block
The south-west entrance is out of shot to the right as various people help rescue the school's contents and load them onto trolleys. The window is that of the modern languages office. To the left of shot is the caretaker's garage, which dates from c.1967. School House is just out of shot behind the fence to the left.

9 - The south-eastern block again, looking across the entire building
Here's a stitch-up panorama of the centre of lower-school, taken from somewhere mid-way along the RE/Classics run. Note the lack of any chimney-like wall pieces, which must all be to the right of shot.
To the extreme left is the garage from the previous photo, and the gutted language lab (occluding the south-west wing). The central chimney can be seen centre-left, while centre right is the collapsing shell of the IT labs (the similar structure beyond the chimney is the main hall). Two ominous black posts stick up from the bottom corridor (I've no idea what they are), and a long radiator runs the length of the classroom wall (right). Most of the wreckage here is made up of tables and chairs, but the bright box structure in the centre of shot is a filing cabinet (one of those cream and brown ones from the late '80s). In the background to the right, beyond the windows of the south corridor and the quad, is the north-corridor, which is what we shall examine next (the roof to the back right is the old gym).