The son of Sir Henry St John-Mildmay, 5th Baronet and his wife, Helena Shaw Lefevre, he was born at Westminster in April 1853.
[4] His participation in the 1882 season was likely cut-short by his service in the Anglo-Egyptian War of July—September 1882, in which he gained the Khedive's Star.
[1] Returning to England following the conflict, Mildmay made two further first-class appearances for Hampshire, against Sussex in 1883 and Kent in 1884.
[6] In 1885, he saw action in the Mahdist War, partaking in the Nile Expedition to relieve Khartoum and was mentioned in dispatches.
[10] Having died without issue, he was succeeded as the 7th Baronet by his younger brother, Sir Gerald St John-Mildmay.