Liz Truss’s decision to sack the Treasury’s top official on her first day in office was “very unusual and very regrettable”, a former cabinet secretary has said, accusing the new prime minister of treating the civil service “improperly”. Robin Butler – who served under Margaret Thatcher, John Major and Tony Blair – said the decision to remove Sir Tom Scholar as permanent secretary at the Treasury would have implications on how well the the department would handle the economic crisis. “If there was ever a time we needed experience and continuity, which is what the civil service provides, it is now. We have a new sovereign, we have a new prime minister and we really need the cement that can hold this system together,” Lord Butler told BBC Radio 4’s The World This Weekend. “I think the politicians are beginning to forget the constitution. The civil service is Her Majesty’s civil service. A government wouldn’t come in and on the first day sack the head of Her Majesty’s defence forces, the chief of the defence staff.” Butler said he was concerned about the politicisation of senior civil service roles. “I think they are behaving improperly towards the civil service. It will weaken them but it will also corrupt our system because one of those great advantages of having an independent, loyal civil service will be compromised.” Before becoming prime minister, Truss railed repeatedly against what she called “Treasury orthodoxy”, notably the predictions that her plan to make large and unfunded cut taxes could increase inflation. Scholar had played a leading role in dealing with the 2008 banking crisis and had worked closely with Gordon Brown and David Cameron before taking the top Treasury job in 2016. It is understood he was told he would be going on Tuesday after Kwasi Kwarteng was appointed chancellor under Truss. Scholar said Kwarteng had decided it was time for “new leadership”. He wished the department “all the best for the times ahead”, adding he would be “cheering on from the sidelines”. Scholar’s predecessor Nick Macpherson called him “the best civil servant of his generation”, adding: “Sacking him makes no sense. His experience would have been invaluable in the coming months as government policy places massive upward pressure on the cost of funding. As Gordon Brown used to say: ‘They’re not thinking’”. Two potential replacements for Scholar who have worked closely with Truss in government are Antonia Romeo, permanent secretary of the Ministry of Justice, and James Bowler, who does the same role at the Department for International Trade.