| Sir Mark Lyall Grant | |
| Honorific-Suffix: | GCMG |
| Office: | United Kingdom National Security Adviser |
| Primeminister: | David Cameron Theresa May |
| Term Start: | 7 September 2015 |
| Term End: | 13 April 2017 |
| Successor: | Mark Sedwill |
| Predecessor: | Kim Darroch |
| Office2: | Permanent Representative of the United Kingdom to the United Nations |
| Monarch3: | Elizabeth II |
| Primeminister3: | Gordon Brown David Cameron |
| Term Start3: | 1 November 2009 |
| Term End3: | May 2015 |
| Predecessor3: | John Sawers |
| Successor3: | Matthew Rycroft |
| Office4: | Director-General for Political Affairs at the United Kingdom Foreign and Commonwealth Office |
| Term Start5: | 2007 |
| Term End5: | 2009 |
| Predecessor5: | John Sawers |
| Successor5: | Geoffrey Adams |
| Birth Date: | 29 May 1956 |
| Birth Place: | Hammersmith, London, England |
| Education: | Eton College |
| Alma Mater: | University of Cambridge |
| Spouse: | Sheila, Lady Lyall Grant |
| Children: | 2 |
Sir Mark Justin Lyall Grant (born 29 May 1956) is a former senior British diplomat who was previously the United Kingdom's National Security Adviser and Permanent Representative of the United Kingdom to the United Nations.
Born in Hammersmith to Mary (née Moore) and Maj Gen Ian Lyall Grant MC,[1] Lyall Grant was educated at Eton College and read law at Trinity College, Cambridge. He was called to the bar at Middle Temple, London before joining the Foreign and Commonwealth Office in 1980.
Lyall Grant was British Permanent Representative to the United Nations (UN) from 2009 to 2015.[2] [3] He held the office of President of the United Nations Security Council four times: in November 2010, March 2012, June 2013, and August 2014.
Lyall Grant was appointed a Companion of the Order of St Michael and St George (CMG) in the 2003 New Year Honours before being promoted to Knight Commander (KCMG) in the 2006 Birthday Honours and a Knight Grand Cross in the 2018 New Year Honours.
On 7 July 2015, Number 10 Downing St announced that Lyall Grant would replace Sir Kim Darroch as the United Kingdom's National Security Advisor on 7 September 2015, with Darroch moving to a different diplomatic post.[4] As of September 2015, Lyall Grant was paid a salary of between £160,000 and £164,999, making him one of the 328 most highly paid people in the British public sector at that time.[5] On 27 February 2017 it was announced that Lyall Grant would retire in April and be replaced by the Home Office Permanent Secretary Mark Sedwill.[6] Since 2017, he has served on the governing board at Eton College.[7]
He was appointed King of Arms of the Order of St Michael and St George in 2022.[8]
His wife, Sheila, is also a diplomat. In April 2012, Lady Lyall Grant, with Huberta von Voss Wittig, made a video appeal to Asma al-Assad, calling on the Syrian first lady to take a stand against violence in her country.[9] The Lyall Grants have a son and a daughter. Lyall Grant's spare time activities include golf, tennis, and bridge.[2]