Patrick Ponsonby was born in Little Heath, Hertfordshire on 10 September 1894, the son of Sydney Alexander Ponsonby (a Banker’s Clerk) and the Honourable Audrey Catherine Ponsonby (née St. Aubyn).  He attended Haileybury College, Hertfordshire.  

He joined the Royal Marine Light Infantry as a Probationary 2nd Lieutenant on 1 October 1912 and was promoted to Temporary Lieutenant on 6 September 1914 having been appointed to the battleship HMS VICTORIOUS on 29 August 1914.  

He transferred to the Royal Navy on 11 May 1915 and served in HMS QUEEN, WEYMOUTH and COCHRANE until 23 December 1916, being promoted to Lieutenant on 11 November 1916.  

He was then appointment to HMS DOLPHIN ‘under training’ on 1 January 1917 then to the Submarine Depot Ship HMS THAMES (4th Submarine Flotilla) at Sheerness ‘for Submarine C5 as First Lieutenant’ on 23 February 1917.   HMS C5 was subsequently based at Middlesborough, Sheerness, and Harwich.  

On 1 December 1917 he was appointed to HMS DOLPHIN (6th Submarine Flotilla) ‘for Submarine H26 as First Lieutenant – standing by whilst completing at Vickers at Barrow’ and ‘on commissioning’.  HMS H26 was then attached the Submarine Depot Ship HMS VULCAN at Blyth to date 1 October 1918.  

On 1 January 1919 he was appointed to the Submarine Depot Ship HMS LUCIA (10th Submarine Flotilla) at Middlesborough ‘awaiting Courses’ and, on 1 February 1919 to HMS VULCAN (14th Submarine Flotilla) at Stornoway ‘awaiting Courses’.  He returned to Barrow in Furness on 1 March 1919 appointed to HMS DOLPHIN ‘for Submarine L19 as First Lieutenant – standing by whilst completing at Vickers’.  On 11 February 1920 he was appointed to HMS DOLPHIN (Reserve Fleet) at Portsmouth ‘for Group H Submarines in Reserve’.  

He completed his ‘Commanding Officer Qualifying Course’ in early 1920 and by 30 October 1920 he had been appointed to HMS DOLPHIN ‘for Submarine H27 in Command’.  He was sent to the Far East with an appointment to the Submarine Depot Ship HMS TITANIA ‘additional for duty in SMs as Commanding Officer’ to date 26 November 1921 and was appointed to the Submarine Depot Ship HMS AMBROSE (4th Submarine Flotilla) at Hong Kong ‘for Submarine L8 in Command’ on 6 January 1922.  

Patrick Ponsonby is reported to have died in the Royal Naval Hospital in Hong Kong on 11 July 1922 after contacting pneumonia and was buried in the Happy Valley Cemetery in Hong Kong in Section 21A.