Boris Johnson has made clear he has no intention of ripping up the stringent new tier system of coronavirus restrictions for England to placate angry Tory MPs, as a row continues to rage about the data underlying the government’s decisions. The prime minister promised to publish what his spokesman called “an analysis of the health, economic and social impact of the tiers approach” before next Tuesday’s vote on the system, and committed to reviewing the tiers on 16 December. But senior MPs have continued to raise concerns about the data underlying the decision-making that led to 99% of England’s population being placed in the top two tiers, with strict limits on socialising. Some believe up to 70 Tory backbenchers could refuse to support the government, leaving Johnson reliant on Labour votes to implement the policy. The chair of the public administration and constitutional affairs committee, William Wragg, wrote to Michael Gove on Friday posing a series of questions, including “can you explain the governance of lockdown decisions?” and “who should we hold to account for ensuring data underpinning lockdown decisions are transparent?”. Johnson gave a robust defence of the new approach, which government scientists have acknowledged is stricter for many people than the rules that were in place before the four-week lockdown. Johnson explained why broad areas had been placed in the same tier – a decision that has infuriated Kent MPs, for example, who resent the entire county facing the toughest restrictions. “The difficulty is, if you did it any other way, first of all you’d divide the country up into loads and loads of very complicated subdivisions – there’s got to be some simplicity and some clarity in the way we do this,” he said on a visit to a Public Health England lab. He added that when an area was placed in a lower tier than an adjacent area where the infection rate was high, “the low incidence area I’m afraid starts to catch up”. The economic analysis document is being put together by officials in the Department of Health and the Cabinet Office. Privately, some government insiders acknowledge that key rebel figures such as Steve Baker are unlikely to be won over by any number of Whitehall bar charts. Lockdown sceptics questioned one of the graphs used in Thursday’s Downing Street press conference, showing a continued rise in hospital occupancy, arguing that official figures showed new admissions to hospitals had begun falling even before the lockdown. “Time and again we are being given data out of context or data that just doesn’t stack up when challenged,” said a former Conservative minister. “The information presented to justify the current lockdown proved to be completely inaccurate. Now it feels as if we are being given selective information to justify these latest measures. The government cannot expect to get the support of backbenchers if the data presented to us all keeps proving to be either dodgy or misleading.” Labour has not yet made a decision on whether to support the new system. Keir Starmer is due to be briefed by government advisers, including the chief medical officer, on Monday. Labour is pressing the government to provide more support for businesses in the areas under the toughest rules, and a clear route out of tier 3. The communities secretary, Robert Jenrick, said on Friday there would be an opportunity for some areas to “de-escalate” to a lower tier before Christmas. But his optimism contrasted with the view of Prof John Edmunds, a member of the Sage advisory committee, who told the BBC he didn’t expect enough data to have emerged by 16 December. “I think that is quite an early time to be able to see what the effect has been,” he said. “For me I think that is quite an early review stage. I can’t imagine there will be huge changes at that point just simply because I don’t think we will have accumulated much data by then.” Johnson has stressed the importance of mass, rapid turnaround testing, as used in Liverpool, in bringing case levels down. Local authorities in all tier-3 areas will be able to apply from next week for a six-week package of support to roll out rapid testing. But with more than 23 million people in tier 3, some areas will have to be prioritised.