No-it’s the whole double glazed panel. You need to know the overall size and the thickness of the 2 pieces of glass overall which contain a bar at each edge also.
If you remove the beads (which hold the glass in place) and take the glass out you will be able to measure exactly the size overall.
Then get yourself down glass replacements
I've measured inside the recess so I've got a rough size but will probably need to get someone out. Got a couple of Pompey glaziers who will likely come round tomorrow.