The resignation of the cabinet secretary, Mark Sedwill, is a serious cause for concern (Mark Sedwill to step down as UK’s top civil servant, 29 June). Genuine Conservatives have always wanted to defend long-established legal and political institutions, partly because of a belief in gradual, evolutionary change rather than revolution based on dogma, and partly because such bodies have been deemed to enshrine decades of accumulated wisdom, which has been transmitted smoothly to the next generation, thus maintaining continuity and stability. However, recent Conservative governments, and their sycophantic supporters in much of the press, have displayed utter contempt for venerated institutions such as parliament, the judiciary, and the civil service, while also pursuing a “culture war” against the BBC and universities. Apparently, any institution that dares to display its “independence” from the government is deemed to be treasonous and subversive, and must therefore be cowed and bullied into compliance and servitude: “If you’re not for us, then you’re against us.” How ironic that the Conservatives have always warned that it was the left that posed the threat to Britain’s democracy, and would ruthlessly use the state to stifle opposition, when it is actually today’s Conservative party that is pursuing a permanent revolution based on a failed and divisive ideology, and wants to silence anyone or anything that opposes them. Perhaps the Conservative party should change its name, because it is certainly no longer conservative, either in thought or deed. Pete Dorey Bath • Britain led the world in creating a professional and independent civil service. With the enforced departures in short order of the heads of the diplomatic and home civil services, plus the appointment of an unqualified political crony as national security adviser, we find ourselves led by deeply flawed politicians who will stop at nothing to destabilise our systems of governance. What is now needed is an unequivocal joint public statement from all remaining permanent secretaries asserting the need for a non-partisan civil service entitled to respect and fair play. Robin Wendt Chester • Politicians seeking a fall guy for their failures, their lack of integrity and their non-observance of the rules is nothing new. In the early 1990s, as the chief executive of a public authority, trying to get politicians to observe the longstanding conventions relating to integrity and transparency, I was told that I had an overdeveloped sense of what was right and wrong. I took it, and I told them so, as a compliment but I had to take the Sir Mark route. He deserves much better treatment, but what can be expected from those who subscribe to the Barnard Castle school of ethics and integrity? David Ansbro Skipton, North Yorkshire • I look forward to Mark Sedwill’s book about his time at the Cabinet Office. After all, it wouldn’t be appropriate to gag a man of his seniority – would it? Anne Cowper Swansea • Your report on the resignation of Mark Sedwill said that special adviser David Frost would replace him as national security adviser. On Radio 4, the education secretary, Gavin Williamson, reassured us that having a political appointee in such a role is “not unusual, it’s what you see in the United States”. Citing Trump’s administration as a model of good governance is not encouraging. Richard Davies Southport, Merseyside