More lives were lost at Grenfell Tower than in almost any peacetime building fire in Western Europe in the last century. How could this fire have happened?  Early in my career, I was close to the enquiry into another tragic fire, that at Summerland in the Isle of Man. The two fires have similarities. I discuss materials in fires, and the problem of confronting low-probability, severe-consequence risks. I ask: in the light of Summerland, why was Grenfell not prevented? I also ask: Is it true that we can un-learn technology?