A bomb under my seat at a polo match in the foothills of the Himalayas; I've been hosted by a man plotting to have me assassinated; I've been shot at, mortared and even had someone come after me with a suicide vest.

[4][15] He was described as the Prime Minister's "first and only choice" to replace Heywood, with no recruitment process taking place and some suggesting the urgency of arrangements for the UK's departure from the European Union as a reason for the quick appointment.

[15][17][18] In a February 2019 interview Sedwill said he would retain his role as National Security Adviser to the Prime Minister since becoming Cabinet Secretary is part of moves to make a success of Brexit.

Following the meeting of the council, the Telegraph reported that it had agreed to allow Huawei limited access to help build Britain's new 5G network, amid warnings about possible risks to national security.

[20] In July 2019, The Times reported that two unnamed senior civil servants had said the 70-year-old Jeremy Corbyn might have to stand down due to health issues.

The article drew an angry response from Labour, which denounced the comments as a "scurrilous" attempt to undermine the party's efforts to gain power.

[21] In November 2019, Sedwill blocked the publication of a document written by civil servants to cost the Labour Party's fiscal plans before a general election.

Shadow Chancellor John McDonnell had complained to Treasury Permanent Secretary Tom Scholar in a meeting arguing it would interfere in the upcoming general election.

He was to be replaced by David Frost, who was Johnson's special adviser and chief negotiator in talks on the post-Brexit trade and security relationship with the EU.

[30] Speaking to the Covid Inquiry, Simon Case and Sedwill described Boris Johnson’s Downing Street as “poisonous”, “mad” and unfit to run the country.

Giving evidence, “I’ve never seen a bunch of people less well-equipped to run a country,” Simon Case, then head official in the Cabinet Office, wrote in July 2020 to Mark Sedwill.