Lionel Pennington was born in Edinburgh on 10 February 1898, the son of Lieutenant Colonel Richard Lionel Arthur Pennington and his wife, Elizabeth Margaret Pennington (née Sutherland).

He joined the Royal Navy as a Cadet at the Royal Naval College Osborne on the Isle of Wight in January 1911.  In December 1914 Midshipman Lionel Pennington was serving in the light cruiser HMS VENUS to which he had been appointed in August 1914.  He then served in the battle cruiser HMS NEW ZEALAND from 1 June 1915 and was onboard during the Battle of Jutland.  He was promoted to Sub Lieutenant on 15 September 1917 and was next appointed to the battle cruiser HMS REPULSE on 16 August 1918.

Promotion to Lieutenant followed on 15 September 1919.  In December 1919 he was ‘training in engineering’ at the Royal Naval Engineering College at Keyham.  An appointment to the light cruiser HMS DELHI followed on 28 April 1921.  In July 1925 he was appointed to the destroyer HMS VIVACIOUS in the Mediterranean Fleet and, in June 1927, he was serving in HMS PRESIDENT ‘for the Engineer-in-Chief’s Department’ as an ‘Engineering Inspector’ to which he had been appointed on 27 February 1927.

He was promoted to Engineer Lieutenant Commander on 15 September 1927, and on 30 June 1931 he was promoted Engineer Commander and appointed to the Royal Naval Dockyard at Chatham ‘as First Assistant to the Manager of the Engineering Department’.  On 23 August 1934 he was appointed as Commander (E) to the cruiser HMS GALATEA – building at the Greenock Yard of Messrs, Scott’s Shipbuilding and Engineering Company Ltd.  He was appointed to HMS PRESIDENT ‘for the Engineer in Chief’s Department’ on 19 November 1936.

On 3 June 1939 he was onboard the new ‘T’ Class Submarine HMS THETIS for the Acceptance Trials.  HMS THETIS was built at Cammell Laird’s yard at Birkenhead and was laid down on 21 December 1936.  During the Acceptance Sea Trial there was a problem with the trim and during the investigations a torpedo tube rear door was opened whilst the bow cap was open.  This resulted in the forward compartments being flooded and the submarine sinking.  During the efforts to rescue the crew and passengers a total of only four escaped before the submarine finally sank with the loss of ninety-nine Officers, Ratings and Civilian personnel.

Lionel Pennington died in the accident.  He was married to Barbara Pennington (née Scott) and was the father of Evelyn Dymoke Barbara Pennington who was fourteen at the time of her father’s death.  He was buried in the THETIS Mass Grave at Holyhead