Robert Middlemist was born in Moretonhampstead, Devon on 20 December 1899, the son of James Menteith Middlemist (Captain. Seaforth Highlanders) & Milly Annette Middlemist (née Clack). He joined the Royal Navy as a Cadet in September 1912. He was promoted to Midshipman on 8 April 1915 and was appointed to the battleship HMS CENTURION on the same date. At the Battle of Jutland on 30 May/1 June 1916, HMS CENTURION was part of the First Division, Battle Fleet. On 21 January 1918 Robert Middlemist was appointed to HMS VERNON.

He was promoted to Sub Lieutenant on 15 May 1918 and was appointed to HMS DOLPHIN ‘for Submarine Training‘ on 8 August 1918 and for the U-Boat U94 on 5 December 1918 for exhibition tours and trials. He was appointed to HMS J5 in February 1919 and to HMS G13 on 29 March 1919. On 10 October 1919 he was appointed to HMS PRESIDENT “for Course of Instruction at Cambridge University“. He served in HMS H44 from 15 April 1920 and was promoted to Lieutenant on 15 May 1920. James Middlemist was appointed to HMS E23 in May 1920. Next was a Gunnery Course at HMS EXCELLENT from 12 September to 17 December 1920.

The date of his appointment to HMS K5 as Navigating Officer was 21 December 1920. K5 was lost with all hands whilst diving to attack battle cruisers during a tactical exercise on 20 January 1921. The reason for the loss was not established but it is believed that the submarine accidentally exceeded its safe diving depth.

Robert Middlemist is commemorated on the Portsmouth Naval Memorial on Panel No. 32.