Editor’s Note: This article excerpt originally appeared in The Weekend Australian Magazine.

In the autumn of 1945, a troop of young Australian soldiers was trudging through the muddy rainforests of New Britain, an island in the east of what is now Papua New Guinea. In that part of the world autumn is much like winter, spring and summer — it rains a lot and it’s hot and humid.

The Australians of D Company, 11th Battalion, were doing reconnaissance in the mountains not far from the town of Rabaul on April 17. They knew Japanese soldiers were nearby, and at least one man was often told to hang back and watch for following enemies. Around 1pm, a group of 20 men from D Company who’d taken a shortcut along a ridge saw something unusual. Sunlight was pouring through the jungle canopy into a cavernous clearing, illuminating a metallic object wedged into the mud. Fearing an ambush, the men at the front of the patrol dropped to the ground. ­Cautiously approaching, they ­discovered to their surprise that it was an enormous plane engine. Corporal Don Angwin, one of the first in line, called back for the patrol’s leader, Lieutenant Ken Backhouse, who came up to investigate.

To find crash debris on the ground was not unusual at that time; warplanes often went down and were sometimes not found for weeks, if ever. But this one was different. It didn’t seem to be a military plane and the men later said it appeared to be very old. Looking for identifying marks, someone grabbed a metal tag hanging off the engine by a wire. Crucially, the information on it was copied onto the margins of a map of the patrol area. Decades later, it would emerge that those numbers and letters matched one plane — an aircraft that had, at the time, been missing for eight years. The fate of this plane and its two occupants remains one of the biggest aviation mysteries in history. The numbers and letters ­corresponded with the Lockheed Electra 10E flown by famed US pilot Amelia Earhart.

In a large tin shed next to David Billings’ ­modest weatherboard home in Nambour, 100km north of Brisbane, there are three gliders in various states of disrepair. One, an old British Slingsby Skylark, has a wingspan of 18m; the wings have to be stored in three pieces just to fit inside the building. Gliding is a passion for Billings, a 78-year-old retired aircraft engineer who speaks with the engaging idiolect of an old Englishman. “I’m hard of hearing,” he says. “Years of jet engines.” Billings is also the main proponent of what has come to be known as the “New Britain Theory” of Earhart’s disappearance. Many ideas have been put forward about her fate, ranging from the well-founded to the wildly conspiratorial — but unlike all the other theories about where she crashed, Billings has evidence and ­videotaped testimony from a group of men who saw the aircraft in the jungle and who have all long since passed away.

Billings closes his eyes as he recalls a news­paper story he read in 1993 about the possibility of ­Earhart’s plane wreck being in New Britain. The article was light on detail but it led him to Angwin, who was the source of the story, and then to other members of D Company. “I met the boys — Don Angwin, Ken Backhouse, Roy Walsh and Keith Nurse — and they recounted to me what they remembered,” Billings says. Angwin told how many years after the war he’d been watching a documentary in which Earhart’s engines — Pratt & Whitney Wasps — were mentioned in passing. The name triggered the memory of the half-buried engine in the jungle; that was the make and model they were told they’d found in 1945.

Angwin then told how another member of the patrol, Len Willoughby, had sent him a map of the patrol area that he’d taken as a souvenir from a pile of discarded equipment in 1945. ­Willoughby had kept the map untouched until he mailed it to Angwin in 1993. When Angwin unfolded it to make a copy, he saw a series of ­letters and numbers ­written in the margins. There are few people in the world who would be able to recognise the ­significance of those letters and numbers — “600H/P S3H/1 C/N1055” — but Billings, who had spent years working in Papua New Guinea, is one. “600HP is obviously horsepower,” he says. “S3H1 is the model of Earhart’s aeroplane engines — S3H1 Wasps, made by Pratt and Whitney.” But the most compelling of the numbers is CN1055. This was the unique construction number assigned to ­Earhart’s airframe.

The series of circumstances that led Billings to the soldiers, their memories and the map was so incredible that Billings’ wife Mary says it was like a “tapestry of chance”. “It was so unlikely, it must have been destined to be,” she says.

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Gazing Skyward TV has featured several articles on David Billings’s efforts to uncover what happened to Amelia Earhart and Fred Noonan. You can find our previous coverage here and here. David also has a website that goes into great detail which you can see here.