Four former ministers and a serving secretary of state will be cross-examined this year in a potentially politically explosive climax to the four-year Grenfell Tower public inquiry. Eric Pickles, the former secretary of state for communities, Brandon Lewis, the current Northern Ireland secretary, and the former housing minister Gavin Barwell will face hours of questioning over claims Conservative-led governments prioritised a “bonfire of red tape” over safety. Senior politicians are likely to be interviewed on how they responded to direct warnings about safety in high-rise blocks from the commissioner of the London fire brigade just weeks before the disaster. James Wharton, a former junior minister and close ally of Boris Johnson, and Stephen Williams, a former Liberal Democrat junior minister, are also expected to give evidence in person. Over three months, the inquiry will turn the spotlight from the actions of combustible materials manufacturers and the consultants and builders involved in the council block’s disastrous refurbishment, to the government that pursued – lawyers for the bereaved claim – “a political ideology which broke free from common sense and safety constraints”. Michael Gove, the secretary of state for levelling up, housing and communities, has already admitted the government “failed people at Grenfell” and told MPs that “on a couple of occasions” it had “not necessarily appreciated the importance of fire safety and not necessarily done everything in the wake of the Lakanal House tragedy [a 2009 tower block fire where six people died] that it should have done.” While the inquiry will look at the actions of governments going back to the 1990s, a principal context will be what David Cameron described in 2012 as his government’s “resolution to kill off the health and safety culture for good”. The bereaved have called for Cameron to give evidence to explain his policy, but the inquiry has not asked him to do so and Lord Pickles will field important questions Pickles was Cameron’s cabinet minister in charge of building safety from 2010 to 2015, and will be asked why the government failed to overhaul fire regulation guidance despite an instruction to do so by the coroner on the Lakanal House fire. The ambiguity of the guidance, which remained in place at the time of the Grenfell disaster on 14 June 2017, was a significant factor in allowing companies and consultants to use combustible materials, the inquiry has heard. In one letter disclosed to the inquiry, Pickles is shown assuring the coroner there would be a “future review” but arguing “fire protection in buildings is a complex subject and should remain, to some extent, in the realm of professionals”. Lawyers for the bereaved have argued the government became the “junior partner” in a relationship with the housebuilding industry, which allowed companies too much control over standards. In 2011 Pickles launched the “red tape challenge” to slash bureaucracy facing business. In the budget that year a new rule was introduced that required a waiver for any change to the building regulations. The inquiry will examine internal Whitehall documents showing how in 2015, a civil service briefing for the then housing minister Lord Wharton, was explicit that the review had been postponed “whilst the department focused its attention on other priorities including the red tape challenge”. Only “lip service” was paid to the commitment to the coroner to review the regulations, Anne Studd QC, counsel for the mayor of London has argued. Pickles has so far told the inquiry in a statement he does not recall “the potential industry use of combustible materials in external cladding systems was ever raised with me”. Pickles is also likely to be questioned on his resistance to introducing sprinklers as a safety measure, which the Fire Brigades Union has told the inquiry would have saved lives at Grenfell. In October 2013, when the Welsh government made sprinklers mandatory for new-build homes, Pickles complained it had “hit the housing market with extra red tape, adding £13,000 to the cost of building a new home”. In fact, a government briefing note disclosed to the inquiry said the amount was no more than £3,000. The inquiry may ask where he got his numbers from. In February 2014, Lewis, a junior minister under Pickles at the time, told parliament that “sprinklers work” but referred to a “one in two out” rule as part of the coalition’s red tape policy and said: “In that context … we want to exhaust all non-regulatory options before we introduce any new regulations.” Ministers are also likely to be asked about their dealings with Sir David Amess, the Tory backbencher who was killed in October. In 2014 Amess chaired the all-party parliamentary fire safety and rescue group, which was pressing Willams, the housing minister, to get on with the building regulations review ordered after Lakanal. Penny Mordaunt, an undersecretary in the department at the time, told Amess that Williams had seen no evidence it was urgent, and that he “was not willing to disrupt the work of the department” by getting on with it. This was “chilling”, the inquiry has heard. Amess’s group replied that it was “at a loss to understand” how independent evidence “which had life safety implications” was not urgent. It said: “Should a major fire tragedy with loss of life occur between now and 2017 … where the matters which had been raised here were found to be contributory to the outcome, then the group would be bound to bring this to others’ attention.” Lord Barwell, Theresa May’s former chief of staff who held the office of housing minister in the year before the disaster, is likely to face questioning over how he handled direct fire safety warnings from the London fire commissioner, Dany Cotton. On 3 April 2017 Cotton told Barwell and Lewis, by that time policing and fire minister, of “mounting evidence of issues of concern within residential buildings and, in particular, blocks of flats” about compartmentation and the impact on the policy of telling people to stay put in the event of a blaze. She said: “We are also concerned about contractor competency, and how this influences compartmentation deficiencies and therefore occupants’ safety.” This was prescient as the compartmentation failed catastrophically at Grenfell, partly because of poor workmanship, and the stay-put policy was kept in place for too long, costing lives, the inquiry has already found. A significant civil servant facing questioning will be Brian Martin, a former building control officer who rose to be a senior adviser to ministers on building regulations. He is likely to be asked what he knew about companies bringing dangerous, non-compliant materials to the market by exploiting confusions in how the building regulations could be met. Michael Mansfield QC, representing some of the bereaved, has alleged Martin “took an attitude that was complacent and collusive with a dangerously out-of-control industry”. In July 2014 Martin emailed a contact at the National House Building Council, which provided building control and warranty services for new-build homes, saying that “reliable sources” had been telling him that combustible foam insulation was being used in cladding on high-rise flats. He referred to polyisocyanurate foam, the kind specified for Grenfell that fuelled the fire and released toxic gas, but all he said was: “The purpose of my email is a friendly warning. You might want to double-check with your inspectors [ … ] that they are on top of this”. The inquiry resumes on 24 January.