When Leslie Sayer’s mother died, his father was working as a head stable lad and found himself unable to support his son. Leslie Sayer thus became a Barnardo’s boy, subsequently joining the Royal Navy as a boy seaman at HMS Ganges at Shotley.

A bright lad, he was selected for signalman and, having served in two cruisers, transferred to the Fleet Air Arm as a telegraphist air gunner or TAG. He joined his first squadron, No 811, in the carrier Furious in 1937.

The crew of the elderly Swordfish biplane — nicknamed the “Stringbag” — consisted of a pilot, an observer and the TAG who had to be able to work the Morse hand key-operated radio and the machinegun. Sayer was promoted to petty officer and qualified as a TAG instructor before a posting to 825 Squadron and the carrier Victorious.

In May 1941, as the TAG in the Swordfish flown by the senior pilot of 825 Squadron, Lieutenant (later Rear-Admiral) “Percy” Gick (obituary, January 22, 2002), Sayer was awarded the Distinguished Service Medal for his part in the first carrier-borne aircraft attack on the German battleship Bismarck. Victorious was newly commissioned and loaded with Spitfires destined for Malta, and the small number of 825 Squadron’s Swordfish crew that had been hurriedly embarked were inexperienced. Gick, who was awarded the DSC, led his sub-flight round twice under heavy fire and in appalling weather conditions to get the best shot, and his torpedo was the only one to hit — unluckily on the armoured belt but damaging a fuel tank. Facing backwards, Sayer was able to verify the hit and transmit the news.

After the catastrophic engagement that ended in the sinking of the battlecruiser Hood with all hands save three, and damage to the battleship Prince of Wales, Bismarck, with the heavy cruiser Prinz Eugen, had disappeared into the wastes of the North Atlantic. A long-range RAF Catalina amphibian from Northern Ireland found her after 32 nail-biting hours. The famously dramatic narrative of the Ark Royal’s air group attacks followed — the first mistakenly on the shadowing cruiser Sheffield and the second achieving a hit on Bismarck’s rudders which allowed Home Fleet battleships, short of fuel, to close and batter her into a wreck that was sunk by torpedoes.

Sayer accompanied Gick and 825 Squadron to the carrier Ark Royal in the Mediterranean and took part in several convoy and land attack operations. He was on board when Ark Royal was torpedoed by a U-Boat. As she took some time to sink, this event became known as a failure of naval damage control doctrine. After being re-formed, 825 Squadron was based at RAF Manston when in February 1942 six Swordfish were dispatched to attack the heavily defended German battle cruisers Scharnhorst and Gneisenau with the Prinz Eugen, making their “Channel dash” from Brest to ports in Germany.

Although more than 300 British aircraft were engaged in support of attacks by Dover-based torpedo boats and a squadron of antiquated destroyers, this powerful force escaped unscathed until Scharnhorst was damaged by a mine off the Netherlands.

Led by Lieutenant-Commander E. Esmonde, who was posthumously awarded the VC, all six Swordfish were shot down; only five of the 18 aircrew were recovered. Sayer, who was Esmonde’s TAG, owed his life to the radar trials off Ailsa Craig that required his expertise at the crucial moment.

He later flew anti-submarine patrols from an escort carrier on convoys to Russia — he recalled it as “a miserable experience”.

He left the Navy at the end of the war, his final posting being to 837 Squadron in the newly built light fleet carrier Glory that arrived in the Far East just as the war was terminated by the dropping of the atom bombs. He subsequently flew for many years with British European Airways as a navigator, recalling early flights in freezing and unpressurised Dakota aircraft.

In 1947 he became the first chairman of the Telegraphist Air Gunner’s Association, subsequently working as editor and secretary on a number of occasions and being appointed MBE for his services. In 1994 Sayer cowrote with Vernon Ball a book Tag in a Stringbag. He was also president of the North Essex Astronomical Society and a leading light in the lively Europa Bures movement, which brings together all the villages in Europe called Bures, Bure or Buren and which will be hosting festivities this summer at Bures St Mary on the Essex/Suffolk border. He was sadly missed at a veterans’ reunion in the carrier Illustrious on November 5.

He is survived by his second wife, Valerie. His first wife and a son predeceased him.

Chief Petty Officer Leslie Sayer, MBE, DSM, wartime telegraphist air gunner, was born on June 5, 1915. He died on November 1, 2008, aged 93