I've seen a few of these and the CFO summed up the issues perfectly - fire travelling unseen through the voids and coming out in unlikely places. They remind me of the old fire travel in lath and plaster buildings and one in particular that stands out for me was the old FA building in Lancaster Gate where a couple of ffs from one of my old stations had to jump out of a first floor window when they became trapped by a rapid escalation of the fire when a section of wall collapsed and the fire suddenly erupted when it found a source of oxygen after being ventilation controlled for some time. The interesting point about the expansion of the floors is interesting; also COBRA is a useful tool in this type of fire but I'd imagine it difficult to control the depth of cut.
A small block in W. London completely collapsed in on itself after the internal supports burnt away - extremely difficult buildings in which to fight a fire.
