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Hello, this is the Grenfell Tower Inquiry podcast, reporting every day the inquiry sits.

I'm Eddie Mayer, and today the inquiry heard from expert witness, Professor Luke Bisby,

from the University of Edinburgh, who's a specialist in fire safety engineering.

His report focuses on how the fire spread around the building.

He told the inquiry that as soon as combustible cladding was fitted to the tower, the advice

to residents that they'd be safe to stay in their flats in the event of a fire should have been

scrapped. If a fire is ignited in a cladding system such as this made from these materials

under any circumstances.

We have to expect it to spread quickly and catastrophically because of the nature of the materials

involved. And on that basis, it is unreasonable to expect compartmentation to be maintained,

and on that basis it is unreasonable to have a stay put policy in place.

Professor Bisbee began his evidence by discussing some of the combustible materials which were used at Grenfell,

starting with the external cladding.

This was fitted as part of the refurbishment of the tower between 2012 and 2016.

The outer layer of the cladding was a rain screen made of two thin sheets of aluminium,

between which there was a core of polyethylene or PE.

Leit Council to the inquiry Richard Millett read from Luke Bisbee's report

in which he said the dangers of using this material were well known.

The fact that thermoplastic polymers, such as PE, present particularly challenging

behaviour as regards its reaction to fire, has been well known and documented for decades. And this fact,

therefore, cannot in my opinion be considered at all surprising by any competent fire safety

...