Peter Twiss joined Fleet Air Arm as Naval Airman 2nd Class in 1939 and trained at HMS St Vincent. In 1940 he trained at 14 Elementary Flying school Elmdon and at FTS Netheravon on Fairey Battles North American Harvards and Hawker Harts. In September 1940 he was commissioned and posted to Yeovilton flying Gloster Gladiators, Skuas and Rocs. He then converted to Bristol Blenheims at Andover
. In November he joined 771 Squadron. 1941 he went to 759 Sqn Yeovilton flying Gladiators and Hurricanes, 804 Squadron Sydenham Northern Ireland
for escort duties including time on merchant ships fitted with catapults.
1942 he flew Fulmars with 807 Squadron HMS Eagle and HMS Argus on the fleet convoys to Malta
where he was awarded his DSC. He was part of the 1st Seafire Squadron fighter support for HMS Furious during the North African landings at Oran
and Operation Torch and was awarded the Bar to his DSC. In 1943 he joined Naval Fighter Interception Unit for Night Fighter training flying Beaufighters and Mosquitos on intruder patrols over the continent where he shot down 2 enemy aircraft. March 1945 he joined the Empire Test Pilots School at Boscombe Down. In 1946 he joined the Fairey Aviation Company as a test pilot and flew Firefly, Spearfish, helicopters, Rotodyne, Gannet, and Fairey Delta 1 & 2. In 1955 he was awarded the Queens Commendation for Valuable Services in the Air and the Derry Richards Memorial Medal In 1956 he was appointed Chief test pilot and on 10th March that year he piloted the Delta 2 on a successful attempt at the World Absolute Speed record achieving an average speed of 1132 mph. He was also awarded the OBE for his services to test flying and breaking the world speed record. In 1960 he went to Fairey Marine in charge of power boats following the takeover by Westland Aircraft.