STAFF at the insulation firm behind one of the flammable materials used on Grenfell Tower joked about their "shit product" and "lies", an inquiry has heard.

Technical team members at Kingspan, which has a insulation factory near Leominster, exclaimed "wheyy" and used "LOL" when chatting after their K15 insulation was only partially tested in an attempt to get it classed as fire safe.

A test to claim Class 0 was only done on a foil facer element of Kooltherm K15, rather than the whole composite material. This allowed it to be technically given Class 0 in England and Wales, but not in Scotland.

To obtain a Class 0 rating meant that a product was considered to be of limited combustibility.

These tests were the subject of an instant messenger chat between technical team members in 2016.

Arron Chalmers told his colleague Pete Moss that K15 "Doesn't actually get Class 0 when we test the whole product tho LOL!".

Adding: "Yeahhhh, tested K15 as a whole – got class 1, wheyy lol".

After initially expressing surprise that the firm had "lied", Mr Moss responded with "Whey, shit product, scrap it".

This was met by more messages from Chalmers, including "yeah, all lies mate" and "alls we do is lie in here [sic]".

That manipulation was also referred to in other internal Kingspan emails as "a bit of a cheat", Tuesday's hearing was told.

These messages were all shown as the inquiry heard evidence from Adrian Pargeter, head of technical and marketing at Kingspan in the UK.

Of the instant messages, Mr Pargeter said: "Reading that it's certainly not the view that they espoused externally.

"It's very disappointing to read that from my perspective."

The actions were described by inquiry lawyer Richard Millett QC as a "thoroughly disingenuous and opportunistic choice of words on your part to conceal the fact that K15 had never passed Class 0 and never would as a composite product".

He added: "You were seeking to perpetrate a fraud on the market, and also to mislead customers into buying products that you knew had failed regulatory fire safety tests."

The inquiry has previously been told that Kingspan sold its Kooltherm K15 insulation with an unrepresentative fire certificate based on a 2005 test which claimed it was safe for use on buildings higher than 18 metres.

These certificates have now been withdrawn from the market.

The firm has previously said it did not provide any advice about the suitability of K15 for use on Grenfell Tower and that the firm only learned a small amount of the insulation had been used on the building after the June 2017 fire, which killed 72 people.

The majority of the flammable insulation used on the tower was made by rival firm Celotex.

The inquiry continues on Wednesday with more evidence from Kingspan.