[2] Born in Hammersmith to Mary (née Moore) and Maj Gen Ian Lyall Grant MC,[3] 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.

[4][5] He held the office of President of the United Nations Security Council four times: in November 2010, March 2012, June 2013, and August 2014.

[10] 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.

Lyall Grant's spare time activities include golf, tennis, and bridge.