He served under David Lloyd George as Minister of Labour between 1919 and 1920, as President of the Board of Trade between 1920 and 1921 and as Chancellor of the Exchequer between 1921 and 1922.

He was educated at George Watson's College in Edinburgh and the University of Glasgow, where he studied Law[citation needed] and was President of the Students' Representative Council.

[citation needed] Horne then spent a year teaching philosophy at the University College of North Wales, before being elected to the Faculty of Advocates (Scottish Bar) in 1896.

[1] During the First World War, Horne became Director of Railways on the Western Front with the honorary rank of Lieutenant-Colonel in the Royal Engineers.

[3] He served under David Lloyd George as Minister of Labour between 1919 and 1920, as President of the Board of Trade between 1920 and 1921 and as Chancellor of the Exchequer between 1921 and 1922.