The first crash-landed at Heathrow in 2008 with no loss of life; the second hit a sea wall at San Francisco during a botched landing in 2013, killing three passengers; and all 298 died when the third was shot down over eastern Ukraine a year ago. Those are the only three confirmed cases of Boeing 777s that have been destroyed. In each case the flaperons - key parts of the wings - were accounted for.

More than 1,000 other 777s are flying. The jet is the long-haul mainstay for many of the world’s airlines. None has reported the loss of a flaperon. That is why investigators are so confident that the debris found on a beach in Reunion in the Indian Ocean is from MH370. If so, it is the first tangible evidence of the Malaysia Airlines jet that disappeared between Kuala Lumpur and Beijing on 8 March 2014, with 239 people on board.

The airline said in a statement in Kuala Lumpur that speculation about the find was “premature”. But the man leading the undersea investigation said he was “increasingly confident” that the wreckage was a flaperon from the missing plane.

The Australian Transport Safety Bureau’s Chief Commissioner, Martin Dolan, said: “There is no other recorded case of a flaperon being lost on a 777.”

Johnny Begue and his fellow association members also found a two-metre (six-foot) long piece of plane wreckage that could be from the missing flight MH370 (AFP)

The debris was loaded on to another Boeing 777 at Reunion’s main airport Roland Garros - Air France’s scheduled 31 July evening departure, AF671, to Orly airport in Paris. It is due to arrive early on 1 August and will then be transported to Toulouse, the home of Boeing’s rival, Airbus.

At a laboratory in the suburb of Balma, the wreckage will be examined by experts from France’s air-accident investigation bureau, the BEA. The bureau has already provided advice on undersea salvage operation, following its two-year search for the wreckage of the Air France Rio-Paris flight, AF447, in the Atlantic.

No explanation has been made for the delay in getting the crucial section of wing to France for further analysis. The debris was found on 29 July. The Independent has learned that there were five flights from Reunion to Paris on 30 July, plus one each to Lyon and Marseille. Yet no attempt appears to have been made to put it on an early departure to France.

MH370 debris - in pictures Show all 7 1 /7 MH370 debris - in pictures MH370 debris - in pictures MH370 debris French police officers carry a piece of debris from a plane in Saint-Andre, Reunion Island. AP MH370 debris - in pictures MH370 debris Police carry a piece of debris from an unidentified aircraft found in the coastal area of Saint-Andre de la Reunion, in the east of the French Indian Ocean island of La Reunion AFP PHOTO / YANNICK PITOUYANNICK PITOU/AFP/Getty Images MH370 debris - in pictures MH370 debris The plane part is being taken to France for further investigation Reuters MH370 debris - in pictures MH370 debris French gendarmes and police inspect a large piece of plane debris which was found on the beach in Saint-Andre, on the French Indian Ocean island of La Reunion Reuters MH370 debris - in pictures MH370 debris French gendarmes and police inspect a large piece of plane debris which was found on the beach in Saint-Andre, on the French Indian Ocean island of La Reunion Reuters MH370 debris - in pictures MH370 debris Johnny Begue, a member of a local shore cleaning association, in Saint-Andre, French Indian Ocean island of La Reunion, holds the remain of a suitcase found the day before on the same site Getty Images MH370 debris - in pictures MH370 debris Searches continued on Friday for other possible MH370 debris along beaches on the island of Réunion AP

Britain has offered expertise from hydrographers and oceanographers to help with the investigation. The Defence Secretary, Michael Fallon, said: “We have offered our best analysts and scientists to help narrow down the search.”

Experts at the UK Hydrographic Office will examine historical data on ocean currents and survey data of the sea floor to narrow down the likely location of the aircraft in the Indian Ocean.

The find has failed to stem the wide range of conspiracy theories about the disappearance. One holds that terrorists from China’s Uighur minority downed the jet off the coast of Vietnam, while another maintains that two Iranians travelling on stolen passports were behind its loss.

The internet is currently alive with suggestions that the debris found in Reunion was planted by the Pentagon to help conceal US involvement with the disappearance.