When, in March 1943, a bemused Guy Gibson, looking forward to some leave at the end of three tours of operations, was told that he was, in double quick time, to form a special squadron for an as yet unspecified “op”, his thoughts immediately turned to the choice of an adjutant, the CO’s invaluable righthand man on the ground who alone can create order from the chaos that is germane to such situations.

Bomber Command’s own candidate for the post had been found wanting, and Gibson thought of Harry Humphries, whom he had come to admire for his administrative abilities during his previous tour with 106 Squadron. “He had been in business in peacetime and everything from Orderly Room clerk upwards in war,” Gibson recalled in his book Enemy Coast Ahead. “He was mad on flying, but his eyes had stopped him . . . a quick call to Group had him posted within 48 hours.”

Humphries was therefore in at the birth of 617 “Dam Busters” Squadron, and he was to look after its members and nurse the alternately boisterous or shattered spirits of its aircrew on the ground from the moment of his arrival until almost the end of the war. In that time he was to serve under all the COs of what was to become the RAF’s most famous bomber squadron.

But at the moment of his arrival at Scampton, such future fame seemed unlikely. As Gibson told him: “I don’t know yet what it’s all about. But I gather this squadron will either make history — or be wiped out.”

Harry Humphries was born in Leicester in 1915 and enlisted in the RAF in 1940. Defective sight put paid to a flying career, but after being commissioned in 1941 he devoted his career to administration.

Within 48 hours of his arrival at Scampton Humphries was able to report to Gibson that 617 was ready to fly. Thereafter his administrative efficiency was a vital component in the smooth running of the squadron, and “Adj” or “Humph”, as he was affectionately known, became an integral part of the Dam Busters’ story. His job ranged from organising aircrews’s flying rations and getting them to the right aircraft in time for take-off, to the sombre business of telling parents by telegram of the death of a beloved son and writing letters to them.

In his own account of the squadron, Living with Heroes, published in 2003, Humphries described the elation at Scampton at the success of the dams’ raid gradually turning to dismay as the magnitude of the casualties gradually became apparent. “I returned to the mess in a daze. I had to send fifty-six telegrams to next of kin. Fifty-six letters to write regretting . . .”

It was Gibson’s first and last raid with 617 Squadron. After more than 170 sorties he was grounded for his own safety and sent on a tour of America. (He later wangled his way back on to operations and was killed in 1944.) Humphries next served under Squadron Leader George Holden, killed on a raid on the Dortmund-Ems Canal very soon after his appointment. It proved to be a grim time for 617, with five out of eight aircraft lost on that occasion. He was succeeded temporarily by Harold “Micky” Martin (obituary, November 4, 1988).

With the loss of more crews in operations against well-defended targets, the continued viability of the squadron seemed almost to be in doubt, but the arrival in November 1943 of Leonard Cheshire (obituary, August 3, 2007) marked a turning point. Cheshire’s evolution of new tactics for marking and bombing enabled the squadron to achieve undreamt of levels of accuracy. His successor, “Willie” Tait (obituary, September 13, 2007) has his place in RAF history, as the man who finally sank the Tirpitz. Finally, under the Canadian Johnnie Fauquier, “tough talking to the point of rudeness, but he led from the front”, the squadron dropped the RAF’s first ten-ton bomb, the “Grand Slam”.

With less than a month to go before the end of the war, Humphries was posted to the Far East theatre. He had been mentioned in dispatches in 1944.

After the war he returned to Leicester and became sales manager of Parker Shoes. He had begun to write his account of 617’s history, and at Cheshire’s request his valuable material was made available to Paul Brickhill for his book The Dam Busters (1951). He also advised on the script of the 1954 film.

Humphries is survived by his wife Ethel and by two daughters and a son.

Flight Lieutenant Harry Humphries, Adjutant, 617 Squadron, 1943-45, was born on May 8, 1915. He died on January 30, 2008, aged 92