Mark Sedwill

During his time as Permanent Secretary, one of the organisations the Home Office is responsible for, MI5, failed to adequately safeguard data. In 2019 Lord Justice Sir Adrian Fulford stated MI5 had a "historical lack of compliance" with sections of the Investigatory Powers Act in 2016.

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. In an interview with Civil Service Quarterly, Sedwill said retaining the post would also ensure a "genuine sense of teamwork across and beyond government".

In April 2019 it was reported that Sedwill had written to ministers on the National Security Council and their special advisers after The Daily Telegraph reported details of a meeting about Chinese telecoms company Huawei. 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. Several cabinet ministers have denied they were involved.

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. Downing Street said that Sedwill would write to Corbyn after the party demanded an inquiry into alleged comments. It is unclear whether he will order an investigation. Corbyn has said the civil service has a duty to be non-political.

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 became acting Cabinet Secretary in June 2018, while Jeremy Heywood took a leave of absence on medical grounds, and was appointed to replace Heywood on his retirement on 24 October 2018. He is the second Cabinet Secretary never to have worked at HM Treasury, and the first whose career has been dominated by diplomatic and security work. He was described as the "Prime Minister's first and only choice" to replace Heywood, with no recruitment process taking place, with some suggesting the urgency of arrangements for the UK's departure from the European Union as a reason for the quick appointment. Prime Minister Theresa May was criticised for allowing Sedwill to remain as National Security Adviser alongside his role as Cabinet Secretary, with speculation that the role was being kept for Europe adviser Oliver Robbins.

In February 2013, Sedwill became the Permanent Secretary at the Home Office, filling the vacancy left by Helen Ghosh. Sedwill replaced Mark Lyall Grant as National Security Adviser in the Cabinet Office in April 2017.

In May 2011, Sedwill took over as the FCO's Director-General for Afghanistan and Pakistan (and thus as the UK's Special Representative for Afghanistan and Pakistan) from Dame Karen Pierce DCMG . He additionally became the FCO's Director-General, Political, in autumn 2012, replacing Geoffrey Adams.

In April 2009, Sedwill became the Ambassador to Afghanistan, succeeding Sherard Cowper-Coles. In January 2010, he was additionally appointed as NATO's Senior Civilian Representative in Afghanistan, to be the civilian counterpart to the ISAF Commander, U.S. General Stanley A. McChrystal and then U.S. General David Petraeus. He was succeeded as ambassador temporarily by his predecessor, Cowper-Coles, and then by William Patey, formerly British Ambassador to Saudi Arabia.

He was appointed a Companion of the Order of St Michael and St George in 2008, and a Knight Commander in 2017.

He then served as the Deputy High Commissioner to Pakistan, based in Islamabad from 2003 to 2005, then the Deputy Director for the Middle East and North Africa Department of the Foreign Office. From 2006 to 2008, he served as International Director of the UK Border Agency, part of the Home Office.

Sedwill married in 1999 and has one daughter. He is a Fellow of the Royal Geographical Society, Fellow of the Institute of Directors and President of the Special Forces Club.

He was then posted in Cairo, Egypt, from 1991 to 1994 as a Second Secretary, then First Secretary in Iraq from 1996 to 1997 whilst serving as a United Nations weapons inspector, then in Nicosia, Cyprus, as First Secretary for Political-Military Affairs and Counterterrorism from 1997 to 1999. He was the Private Secretary to the Secretary of State for Foreign and Commonwealth Affairs (Robin Cook and later Jack Straw) from 2000 to 2002 in the run-up to and preparations for the 2003 Iraq invasion.

Sedwill joined the Foreign and Commonwealth Office (FCO) in 1989 and he served in the Security Coordination Department and the Gulf War Emergency Unit until 1991.

Sir Mark Philip Sedwill KCMG FRGS (born 21 October 1964) is a British diplomat, public policy analyst and senior civil servant who has served as Cabinet Secretary and Head of the Civil Service since 2018. He has served as National Security Adviser since 2017. He previously served as the United Kingdom's Ambassador to Afghanistan from 2009 to 2010 and as the NATO Senior Civilian Representative in Afghanistan in 2010. He was the Permanent Secretary at the Home Office from February 2013 to April 2017.