Aubrey Parnell joined the Royal Marines as a probationary 2nd Lieutenant on 1 Jan 1934. After completing RM Young Officer training on 19th June 1936 he was appointed to HMS Rodney as 2nd Subaltern of the RM Detachment and an Officer of the Watch. On 4th January 1938 he then moved to HMS Glorious as Second RM Officer.
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Parnell then attended No 3 Naval Pilots Course from 6 March to 7 May 1939 at Rochester, and then 8 May to 4 November 1939 at No 1 FTS, Netheravon. On completion he was directed to the TSR stream.
From 6 December 1939 to 14 January 1940 he attended Deck Landing Training RNAS Donibristle, conducted by 769 Squadron. Here he conducted dry deck landing training or ADDLs (Airfield Dummy Deck Landings) only with students practicing their approaches to a 'dummy deck' marked on the airfield.
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From 15 January 1940 to 30 April 1940 he was appointed to HMS DAEDALUS for TSR training at RAF Gosport. It was here that he was involved in an accident where when flying Swordfish serial number L7650 he hit the water when pulling out of a dive during a training attack on HMS Malahne. He was rescued off the Needles by HMS Philante, being hauled aboard by his friends Overbury and Shute. Although he continued his flying career, it seems that he sustained a back injury in this accident which would later see him medically discharged from the Corps.
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From 1 May to 26 May 1940 he underwent further training at RNAS Ford with 750 Squadron. His records then show that he was appointed to 823 Squadron in HMS Glorious from 27 May to 6 Jun 1940, although it seems that he was not a part of the half of 823 Squadron that were embarked on Glorious when she was sunk on 8th June 1940. This was the end of Parnell's flying career, and records do not show why.
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He then returned to Corps duty where he served from 23 July to 17 November 1940 with Plymouth Division and then 18 November 1940 to 6 February 1941 with Chatham Division. From 7 February 1941 to 10 March 1943 he was appointed to HMS London as OCRM where it is believed that he took part in several arctic convoys.
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From 11 March to 28 March 1943 Parnell was appointed back to Plymouth Division and then from 29 March to 16 December 1943 he was with 104 RM (Training) Brigade. Then from 17 December 1943 to 4 Junuary 1944 he was appointed to Depot RM, Lympstone and RMITC, Dalditch as a Company Commander. He then again served with Plymouth Division from 5 June to 4 August 1944 before on 5 August 1944 his Service Record states: “Retired on account of medical unfitness”. It is assumed that this was on due to his back injury sustained in his earlier accident.

He died in 1995.