Professor Macmillan is the great granddaughter of David Lloyd George. She is a Canadian historian and provost of Trinity College; a former Warden of St Anthony’s College, Oxford. She is a renowned historian on the British Empire in the late 19th and early 20th centuries.

In 2017 she gave a LSW lecture, ‘David Lloyd George: The Peacemaker’, to mark the centenary of Lloyd George’s appointment as Prime Minister. She was the 2018 Reith Lecturer on the theme of war under the title ‘The Mark of Cain’.

She has been immensely successful as an historian. Her book Peacemakers: The Paris Peace Conference of 1919 and Its Attempt to End War won the Duff Cooper Prize for outstanding literary work in the field of history; the Hessell-Tiltman Prize for History; the prestigious Samuel Johnson Prize for the best work of non-fiction published in the United Kingdom; and the 2003 Governor General’s Literary Award in Canada.

Professor Macmillan is a public intellectual as well as a distinguished author of numerous books and articles. She regularly comments on public affairs in the media, and was one of 200 celebrities who signed a letter to The Guardian opposing Scottish independence.