Theresa May and Boris Johnson let the former chief Brexit negotiator Olly Robbins and other civil servants hang out to dry after they became “targets for political attacks”, an investigation into Whitehall’s role in the Brexit drama of the past four years has found. The independent thinktank the Institute for Government (IfG) spent months talking in confidence to Whitehall sources including officials, ministers and special advisers, to shine a light on the behind-the-scenes experience of some of those involved in one of the most controversial chapters in British political history. Among the moments highlighted by the study was when Johnson put civil servants in an “immensely difficult position” last October when he threatened to leave the EU without a deal in breach of the Benn Act. “Under the civil service code 33, civil servants cannot help ministers break the law,” says its report, The Civil Service After Brexit. On a more prosaic level it also reveals the difficult decision-making and sheer exhaustion suffered by officials in the run-up to the first Brexit deadline of 29 March last year. It tells of civil servants “huddling round” a single printout of a complex and lengthy no-deal tariff schedule because of anxiety about leaks, of staff having to go to dark rooms to access documents on secure computers, and how a generous offer of “firebreak” holiday after the second no-deal deadline on 12 April 2019 led to droves quitting their jobs unable to face a return to the Brexit bedlam. But the study also found that the task of delivering Brexit “exposed weaknesses in the civil service”, with both ministers and officials failing to be upfront about the “severe political, and economic consequences no deal could have in Northern Ireland”. Maddy Thimont Jack, senior researcher at the Institute for Government, said: “Brexit demonstrated the very best of the civil service. It managed to unpick a 47-year relationship with the EU in less than three years, working under immense pressure and to extremely tight timelines. But the task is still not complete and the tensions that Brexit exposed – particularly, between ministers and officials – have not necessarily gone away.” Those who spoke to the thinktank heavily criticised May’s relationship with the civil service. She did not offer any “significant protection” to Robbins after he was openly attacked by hardline Brexiters, accused of “freelancing” and peddling a pro-EU line in Brussels. “The prime minister was notably silent: she offered no support to her key adviser, who was taking personal and professional attacks as a result of her policy decisions,” the report notes. The former head of HMRC Jon Thompson received two death threats after he said May’s “maximum facilitation” border proposals would cost businesses up to £20bn a year. Instead of defending his position as the widely respected chief civil servant at the HMRC, May let her spokesman dismiss Thompson’s analysis as “speculation”. The report concludes that the near breakdown of May’s government and lack of clarity left civil servants trying to build consensus through “tried and tested methods of ambiguous wording and ingenious drafting” something familiar to fans of the TV sitcom Yes Minister. Johnson also used the weapon of silence when civil servants came under attack, the IfG found. Most notably, he refused to defend the UK’s ambassador to Washington, Sir Kim Darroch, when diplomatic emails about Donald Trump’s administration were leaked. Johnson was frontrunner for the Tory party leadership at the time. “Excessive secrecy on Brexit” was another complaint from inside Whitehall with the “over-classification” of documents as “secret” creating unnecessary problems for civil servants. Officials had to rely on super-secure Rosa terminals, put in place by the National Cyber Security Centre, rather than their own computers. “Secrecy caused a lot of unnecessary stress in the run-up to 29 March 2019, with far too few people having access to vital documents. The concerns were leaks – but throughout this period it was mainly the political teams in departments, not officials working on Brexit readiness or negotiations, that were responsible for leaking,” the report says. Vast improvements were made under Michael Gove when he was appointed as head of exit operations (XO) and no-deal planning, the authors conclude. With a dashboard involving 350 milestones and secrecy levels dropped, the new body is said to have moved swiftly “more like a programme management board … than a cabinet committee”. Ultimately the pace was unsustainable and its focus was narrow: to avert the immediate chaos of crashing out of the EU rather than the longer term consequence for the country. But for its flaws, it proved a model that was easily adjusted and used to effect in the coronavirus response, mixing officials and ministers on a cross-departmental basis, the study found.