Explosive evidence about the tensions and disagreements between the then prime minister Boris Johnson, his ministers and the country’s top scientific advisers at key moments during the Covid-19 pandemic is expected to be made public this week at the official inquiry into the crisis. On Monday, Sir Patrick Vallance, the government’s former chief scientific adviser – whose incendiary private diary entries are being quoted selectively at the inquiry – will give evidence at an all-day session on Monday that looks certain to cast new light on the chaos in government as the virus swept across the globe. Vallance will be followed in the witness box by the other top scientists who flanked ministers at the televised daily Covid press conferences. Prof Chris Whitty, the chief medical officer for England, will make an all-day appearance on Tuesday. Then on Wednesday, Prof Jonathan Van-Tam, the former deputy chief medical officer, and the current chief scientific adviser, Prof Dame Angela McLean – who described the-then chancellor Rishi Sunak as “Dr Death” in the weeks following the Treasury- inspired “eat out to help out” scheme in August 2020 – will appear before the inquiry. One of the issues that is certain to be explored is whether the scientists were adequately consulted at key moments, including about the eat out to help out scheme, in which the public were offered a discount on restaurant bills to encourage them to eat out. The inquiry is also likely to examine whether the scientists found themselves under political pressure to toe the line as part of the government team, with the result that the true extent of the dangers that they knew existed was not conveyed to the public. One former government minister with knowledge of the Covid threat at the time said: “In the early days, there was a political imperative not to overstate or overreact. “These scientists were not accustomed to finding themselves in Downing Street, alongside politicians at televised press conferences,” the minister said. “They will obviously have felt under pressure and couched what they said. That was certainly an issue.” One potentially difficult area for the scientists could be evidence that has already emerged which suggests that they had on several occasions seemed to have been stronger in their warnings about the Covid pandemic in private than they were in public. It has already emerged that Dominic Cummings, Johnson’s former chief adviser, told a No 10 aides’ WhatsApp group on 6 February 2020 that Vallance had just said to him that the virus was “probably out of control now and will sweep the world”. However, on 25 February 2020, Whitty and Vallance had briefed journalists saying that data from China suggested it was still possible to contain the virus. Vallance added: “We’ve always taken the view that this may either be containable or it may not.” One extract from Vallance’s pandemic diary that was released to the inquiry read: “Number 10 chaos as usual. On Friday, the two-metre rule meeting made it abundantly clear that no one in Number 10 or the Cabinet Office had really read or taken time to understand the science advice on two metres. Quite extraordinary.” Vallance and Whitty said in their original witness statements that “had they been consulted” on the eat out to help out scheme at the time, they would have advised against it because they suspected that it would increase transmission of Covid-19 at a crucial time in the fight to control the virus in the UK.