A senior official has admitted the government knew 15 years before the Grenfell Tower disaster that plastic-filled cladding panels – which fuelled the fatal fire – burned “fast and fierce” and he believed they should not be used on tall buildings. But the results of tests were not published, and on Monday Anthony Burd, the principal fire safety professional and later head of technical policy in the government’s building regulations division from 2000 to 2013, denied there was a cover-up. The taxpayer-funded tests showed the cladding panels failed “catastrophically”, with flames reaching 20 metres into the air within five minutes. Similar panels went on to be used on more than 400 high-rise blocks, including Grenfell, where they were the main cause of the spread of the fire on 14 June 2017 that killed 72 people. Burd said the results should have been published but denied that this did not happen because the government feared it would trigger “an immediate cladding crisis” and was afraid of the response of the companies who made the materials. He told the inquiry that the damning results had instead “fallen down between the department and Building Research Establishment”, which the government commissioned to test 14 cladding systems in large-scale fires, including five with rainscreen panels, all of which failed. Nor did the government investigate how many buildings may already have been built with the material, and the test results were not made available for a review of fire safety regulations in 2005. They only emerged after the Grenfell Tower public inquiry started its work. Burd is the first government official to give evidence to the inquiry, which is currently examining how successive administrations, from Labour onwards, liberalised building regulations. It is focusing on how combustible insulation foams and aluminium composite panels (ACM) filled with a plastic core that burns like petrol came to be allowed on Grenfell and thousands of other homes. It has already heard how Arconic, which made the combustible panels on Grenfell, targeted the UK market for sales of its most combustible polyethylene-filled panels because of less stringent requirements. Richard Millett QC, counsel to the inquiry, asked Burd: “Do you accept that you, the British government, was aware from this time on, 2002, how ACM with a polyethylene [PE] core panel could behave in a fire?” Burd said “I would recognise, yes, that we had more insight in terms of this kind of performance.” The testing report compiled for Burd, at the time working in the office of the deputy prime minister, said the ACM panel performed so badly that the rig had to be extinguished early. Under a European classification of combustibility, the panels were likely to be ranked as D, which meant they should not be used on tall buildings. The safest class is A. “It’s a very fierce, fast fire,” said Burd. “This sort of product would not have been acceptable under the building regulations.” But under a separate UK system that measures only the spread of fire across the surface of a material, they were rated as class 0, which gave some users confidence that they could be used under building regulations, partly because guidance diagrams suggested that. Asked if the government considered making it clear after the tests that this kind of product should not be used above 18 metres, Burd said he understood that the building regulations guidance at the time did not allow this product. Asked whether anybody in the department considered alerting builders, local authorities, building control bodies or building owners to the “obvious dangers”, Burd said those bodies were part of an industry group consulted by government and there could have been discussion with building control representatives in that forum. “Was any consideration given by government – you in particular – about whether any specific intervention into the use of PE-core ACM above 18 metres was necessary?” Millett asked. “I can’t recall specifically,” Burd replied. The inquiry continues.