Kingspan commissioned and deliberately “gamed” tests on competitors’ insulation in order to “plant seeds of doubt” in the corridors of power about the safety of non-combustible materials after the Grenfell fire, the inquiry heard yesterday.

It was told the Irish construction giant also hired a leading firm of political lobbyists straight after the tragedy in a bid to influence key decision-makers including ministers and Judith Hackitt in an attempt to discredit rival products and avoid a ban on combustible materials.

Kingspan’s technical and public affairs director Adrian Pargeter denied they rigged the tests but admitted they had deliberately set them up to perform poorly as part of a “political engagement plan” which was enacted with the knowledge of Kingspan’s billionaire chief executive, Gene Murtagh.