Yes, I know, but I wasn't talking about flammability. What I was talking about was ...
.... and the "behaviour in the face of heat or fire" I was talking about was primarily melting (and distorting, falling apart etc.).... given how that material behaves in the face of heat or fire.
Having said that, in terms of 'flammability', I very much doubt that, despite what your link says, BS7671 (or the LFB) would now accept PVC as being an acceptable material for a domestic CU!
Kind Regards, John