The Royal Australian Air Force confirmed on Wednesday it had identified Beaufort Aircraft A9-186 from Number 100 Squadron, four years after the plane’s crash site was first discovered.

The discovery was made by an Ocean Ecology dive team working for billionaire mining magnate Andrew “Twiggy” Forrest as part of an ongoing search for his uncle, Flying Officer David Forrest, who was lost during a mission at Gasmata in the Bismarck Archipelago in the Pacific nation while piloting a similar RAAF 100SQN Beaufort.

In February 2022, Dr Forrest’s team returned to the crash site to identify the aircraft.

Air Marshal Robert Chipman said the identification mission involved the use of specialist divers working on an aircraft extensively damaged by fire and covered in layers of sediment and marine growth.

“The aircraft identity plate and cockpit lever were recovered from the site and will be returned to Australia under a permit granted by the PNG National Museum and Art Gallery,” Air Marshal Chipman said.

The wreck site of the A9-186, which was first reported missing in 1943, is located 43 metres below sea level.

The identities of the plane’s four crewmen, Warrant Officer Clement Batstone Wiggins, Warrant Officer Russell Henry Grigg, Flight Sergeant Albert Beckett and Flight Sergeant Gordon Lewis Hamilton, have also been confirmed, Defence said.

“Small amounts of bone material recovered during the identification mission were analysed by anthropologists and DNA specialists,” Air Marshal Chipman said.

“The RAAF’s HUWC team collated the evidence and a Defence Identification Board identified the remains as those of Warrant Officer Clement Batstone Wiggins and Warrant Officer Russell Henry Grigg.

“Unfortunately, it’s with a heavy heart we can confirm that no remains of the other two crew members, Flight Sergeant Albert Beckett and Flight Sergeant Gordon Lewis Hamilton, were recovered.

“We will continue to strive to find, recover and identify our missing service personnel as part of our commitment to honouring their service and sacrifice for our nation.”

A memorial service for the four war heroes is booked for April 26 at RAAF Base Amberley in Queensland.

Mary and Frank, the two surviving children of Warrant Officer Grigg, expressed their gratitude to Dr Forrest in a letter, writing of their gratitude for his mission to discover the final resting place of his uncle.

“We will be forever indebted to you for your generous and enduring efforts to locate your father’s brother,” they write.

“It means the world to us to finally know our father’s resting place.”

In an emotional interview with A Current Affair, Dr Forrest said his search for his Uncle was propelled by a sense of gratitude for Australia’s service personnel.

“It (the search mission) is an investment which is being made for the heritage of Australia, and the closure of tragedies and if it can do anything, it is to continue to draw attention to how very grateful every Australian must be for those youngsters who died,” he said.

Air Marshal Chipman said no further recovery was planned for the crash site.