He was the son of Sir James Clerk, 7th Baronet and Jane Calvert Henderson.
Among his siblings was Susan Edith Clerk (wife of Sir Alan Seton-Steuart, 4th Baronet).
[1] In 1872, he was a Lieutenant in the 2nd Life Guards before becoming Captain of the Edinburgh County Militia and Major 1st Administrative Battalion Midlothian Rifle Volunteers.
[3] He was a Lieutenant-Colonel and Honorary Colonel of the 3rd Battalion, East Surrey between 1899 and 1904 during which time he fought in the Boer War.
[1] On 4 January 1876, Clerk married Aymée Elizabeth Georgiana Millikin-Napier (d. 1947), a daughter of Sir Robert Milliken-Napier, 9th Baronet and Anne Salisbury Meliora Ladaveze Adlercron, at St. John's Church, Johnstone, Scotland.