In Second World War night bombing operations, the role of the tail gunner was at once vital to the security of the aircraft and its crew — and the least enviable one. Since German night fighters almost invariably attacked from the stern, he was the pilot’s “eyes”. Time and time again, aircraft captains and their crews owed their preservation to the alertness and professionalism of the man in the rear turret. The warning cry from aft: “Corkscrew starboard — Go!” was something any captain acted on instinctively.

Clearly, the rear gunner was also in the direct line of fire from a stern attack and was generally the first man to die if the bomber was hit. Many a Lancaster or Halifax arrived home from a raid with its rear turret missing, simply destroyed by the power of streams of 20mm, 30mm or even 37mm cannon shells from the night fighters, against which its mere .303in (7.7mm) machineguns were pitted.

Given such circumstances it was rare for a bomber’s air gunner to become the equivalent of an “ace” (five kills) himself. Yet that feat was achieved by Wallace McIntosh, who in two tours of operations with 207 Squadron (one manning the mid-upper turret) shot down eight enemy aircraft (three shared) to become the most successful air gunner in Bomber Command.

His most spectacular sortie was on the night of June 7-8, 1944, when his Lancaster, piloted by Wing Commander John Grey, was one of a force of 112 Lancasters and ten Mosquitoes that flew from RAF Spilsby in Lincolnshire to attack a German tank park secreted in woods near Cerisy-la-Forêt, some 20 kilometres inland from the coast between Bayeux and St Lô. The D-Day landings had taken place not 48 hours before, and the elimination of the threat of a counter-thrust by German armoured forces was of the utmost importance.

Not long after they had crossed the Normandy coast, McIntosh spotted a Junkers Ju88 closing in from astern and ordered his captain to corkscrew. At the same time he and the mid-upper gunner, Pilot Officer Larry Sutherland, a Canadian, opened fire on the night fighter, which burst into flames and plunged earthwards. Almost immediately another Ju88 assailed them, but this, too, perished under the combined attack of the two turret gunners, exploding in mid air.

With this threat eliminated, Grey resumed course for Cerisy where a heavy attack was delivered on enemy tanks and fuel dumps as well as an important road junction. The air gunners’ work was not yet over for that night. As it approached the coast on the return flight, Grey’s Lancaster was attacked by yet another night fighter, this time a Messerschmitt 110. Again, McIntosh and Sutherland opened fire and the Messerschmitt caught fire and crashed into the sea.

There was jubilation at Spilsby when this feat was reported at debriefing, and on learning of it at Bomber Command HQ, High Wycombe, “Bomber” Harris sent his congratulations. Both gunners were awarded the DFC.

For McIntosh the RAF had represented an escape from a most unpromising start in life. He was born in 1920 in Tarves, Aberdeenshire, the illegitimate son of a teenage unmarried servant who gave him to her parents to bring up.

It was a wretched upbringing. His grandparents, farm labourers, were often unemployed and travelled in search of work. McIntosh was adept at poaching as a boy before becoming a farm labourer and then gamekeeper himself.

He joined the RAF as an aircraftman in 1939, but was employed only in a ground capacity until being selected for aircrew training in 1943, and qualifying as an air gunner. He was posted to 207 (Lancaster) Squadron, in which he served as a mid-upper turret gunner.

Among operations in which he participated was the series of destructive attacks on Hamburg that summer, which had been ominously codenamed Gomorrah. At the end of his first tour, during which he shot down two enemy aircraft, he was awarded the Distinguished Flying Medal.

McIntosh was commissioned and after a rest from operations was, in February 1944, posted again to No 207, this time as rear gunner in the aircraft of Grey, who was the squadron commander.

On the night of May 3-4, 1944, No 207 joined a force of 346 Lancasters and 14 Mosquitoes attacking a miliary camp and weapons and equipment store at Mailly-le-Camp in Champagne, part of the effort to disrupt the German capacity to react to the impending Allied invasion. The Mosquitoes marked the target accurately but faulty communications led to a delay in the arrival of the main bomber force.

As a result the night fighters were alerted and airborne by the time the raiders appeared and 42 of them — more than 11 per cent — were shot down. Grey’s aircraft was attacked by an Me110, which McIntosh shot down.

Next came McIntosh’s “three-in-a-night” effort over Normandy, and in July he shot down two more night fighters during a raid on Stuttgart. In December, at the end of his second tour, he was awarded a Bar to his DFC. He had flown a total of 55 sorties.

McIntosh remained in the RAF after the war, but left the service in 1948 and worked first as an agricultural salesman in Montrose and Elgin, and later in management for Elbar Farm Services in Elgin.

After finally retiring in 1985 McIntosh undertook a sponsored tour of former bomber stations to raise money for two memorials to 207 Squadron aircrew killed in action. He was a staunch supporter of his squadron association and of the Air Gunners’ Association.

His wife died in 1989. He is survived by a son and two daughters.

Flight Lieutenant Wallace McIntosh, DFC and Bar, DFM, wartime air gunner, was born on March 27, 1920. He died on June 4, 2007, aged 87