After working as a researcher for Videotext Communications in 1998, Turner joined the
Cabinet Office that year and was Secretary to the Better Regulation Taskforce, 1998–1999, then
Secretary to the Economic and Domestic Committees of the Cabinet, 1999–2000. After serving as Private Secretary to a Minister of State, 2001–2002, Turner was Deputy Team Leader in the
Prime Minister's Strategy Unit, 2002–2003, and
First Secretary at the
British Embassy in Washington, DC, 2003–2006, joining the
Foreign, Commonwealth and Development Office in 2005. Turner served as
High Commissioner to Kenya from 2012 to 2015. During his time in Kenya he led the UK response to the
Westgate Mall terrorist attack and the UK's reconciliation with the
Mau Mau. On his return to the UK in 2016 Turner led the London Syria Conference for No 10, raising $12 billion for Syrian refugees. In 2016 he became Director General for the Middle East and Africa and then acting Political Director General. From 2017 to 2019 he served as Prime Minister
Theresa May's international affairs advisor and Deputy National Security Advisor. In this role he was also senior responsible owner for the £1.25 billion
Conflict, Stability and Security Fund. Turner served as
High Commissioner to Pakistan from 2019 to 2023 before becoming Political Director of the Foreign, Commonwealth and Development Office. In May 2025 it was announced that he would succeed Dame
Barbara Woodward as
British ambassador to the United Nations. alongside a number of other candidates including
Mark Sedwill,
Richard Moore and
Lindsay Croisdale-Appleby. In December 2025 Turner was appointed as Ambassador by Prime Minister
Keir Starmer. In April 2026, remarks made by Turner in February 2026 during an event in
Washington, D.C. addressed to British students were made public; these included comments on Starmer being "on the ropes" over the Mandelson scandal, criticising the lack of response to the
Epstein files in the US (as compared to the UK), and criticising the "
special relationship" as a "nostalgic" and "backwards-looking" term when applied to US-UK relations, saying that the one country with a real "special relationship" with the US was Israel (this was said shortly before the US-Israeli strikes on Iran that led to the
2026 Iran war). The Foreign Office clarified that these were private, informal comments and not the UK government's official position. == Honours ==