"The cladding system is combined polyaluminum sheets with a filler of polyethylene. And that is what has caused the problems, because the polyethylene melts at a very low temperature and it catches fire. It is basically like a candle which is sandwiched between two sheets of metal."
"We have seen those fires before. There was one in 2014 in Melbourne, Australia, but those didn't enter the flats, because I understand the flats were sprinklered. In Britain, we didn't have these flats sprinklered, and therefore the fire was able to enter the flats quite rapidly."
[Arnold Tarling, Fire protection specialist]
Another problem, of course, is that once alight the burning of the cladding produces thick toxic smoke.