Major Sir Schomberg Kerr McDonnell, GCVO, KCB, FSA (22 March 1861 – 23 November 1915)[1] was a British Army officer, politician, and civil servant, who was for a number of years Principal Private Secretary to the Prime Minister.

[3]: 39 [4] In 1888 Kerr McDonnell was appointed Principal Private Secretary to the Prime Minister, Lord Salisbury, and served as such while he was in office until 1892, and again from 1895 to 1902 (with a short interval while he fought in South Africa in 1900).

In failing health, Lord Salisbury resigned as Prime Minister in July 1902, and Kerr McDonnell received a non-political appointment, as Secretary to the Office of Works,[5] a position he held until 1912.

This corps was raised and equipped by the City of London for service during the Second Boer War, left for South Africa in January 1900, and returned in October the same year.

McDonnell served as Chief Intelligence Officer for the London District from the outbreak of the First World War until early 1915 but was then sent to Flanders, as a Major in command of the 5th battalion Queen's Own Cameron Highlanders.