Sir Mark Sedwill: UK's top civil servant to stand down as cabinet secretary and national security adviser The UK's top civil servant and national security adviser to Boris Johnson is stepping down, the government has announced. In Gove we trustPolitical nemesis to indispensable ally: Michael Gove is now arguably the most important minister in Boris Johnson’s government. Who is Mark Sedwill and why is the top civil servant resigning?Departure of career diplomat seen as victory for PM’s chief aide Dominic Cummings Sedwill's departure is just the start of wider upheaval in WhitehallDominic Cummings’ disdain for the civil service will bring more than mere changes in personnel Dominic Cummings is right about civil service failingsDuring the war, while he was looking out for fires on the roofs of Whitehall, Harold Wilson bumped into another temporary recruit to the civil service by the name of John Fulton. Wilson was so Mark Sedwill was a roadblock to Dominic Cummings's vision for the civil service – so he had to go | Andrew GriceThe cabinet secretary was subject to hostile briefings that made clear he wasn't welcome. But any team manager knows that you don’t get the best out of your players by telling them they are all useless Mark Sedwill expected to quit as UK's top civil servantCabinet secretary at odds with Dominic Cummings and a target of negative briefings Relationship between No 10 and Mark Sedwill was no longer tenableRumours of rifts between ‘securocrat’ and PM’s staff had dogged Westminster for weeks Minister takes aim at civil service 'group think'A less London-centric and more commercial approach is needed to big decisions, Michael Gove says.