But then it changed the chemical composition of the product in 2006 and retested. This time the result - in the words of a Kingspan employee - was "a raging inferno". Nonetheless, it carried on selling the product using this testing.

This test - which we today learned has been withdrawn (I have more copy to write) - has helped ensure this product has been used on literally thousands of high rises around the country and the world.

If that's enough, we also learned that the use of desktop studies - a route to compliance without testing - was introduced after Kingspan specifically lobbied industry bodies for it in 2014. We are "slowly educating the NHBC" it said of one industry body.

Celotex. We already knew they had withdrawn their test (from 2014) because of the undeclared use of fire resisting boards to fortify crucial barriers. Today Ms Barwise said these "stopped the flames in their tracks".

She also said both firms had made use of fire retardants to get their products through testing. In the words of a research paper prepared by Saint Gobain (Celotex parent company) this was specifically done 'in order to pass unrealistic fire safety tests'

Arconic. We knew the firm was aware its ACM cladding product used on Grenfell was testing to Class E and being marketted as Class B/Class 0 (a much higher). A member of the team is said to have written in 2011: “It’s hard to make a note about this… because we are not clean.”

In a major new revelation, she said the American president of the multinational firm was made aware in April 2015 that the product used on Grenfell was "Euroclass C to E" and "flammable"

We have also heard opening statements from Arconic and Celotex. Arconic's QC said its product had been had been "misused" in a way that was "entirely peculiar to Grenfell" and "could not have been predicted".

Celotex's QC (who is mid-statement) emphasised the product's combustibility was made clear and said the team designing the cladding failed. "These failings were fundamental and should have been identified by building control. None of these matters was Celotex's responsibility,"