Official confirmation that the wreckage came from a Boeing 777 jet may not come for some time as it is not expected to arrive in a specialist laboratory in France until the weekend. The piece, which is about 2m to 2.5m long, is thought to be part of a control surface from an aircraft wing and photographs have started to circulate around the world purporting to show a part number — "657 BB" — stamped on its interior. That number reportedly corresponds to a code in the Boeing 777 maintenance manual, which identifies it as a right-hand side flaperon — a moveable control surface that is located about midway along the wing of the twin-engined jet.

How would that prove it comes from flight MH370?

In short, it would not conclusively as the part number is not thought to be aircraft specific, only aircraft-type specific. But it is almost inconceivable that it has come from any other 777. That is because only four other 777s have been written off due to accidents since the aircraft type entered service in 1994. None of those were lost over the sea and all are accounted for, including the aircraft that operated Malaysia Airlines flight MH17, which was shot down over Ukraine last year. Two others — a British Airways aircraft in 2008 and an Asiana aircraft in 2013 crash-landed at London Heathrow and San Francisco airports, respectively. An Egyptair 777 caught fire on the ground at Cairo airport in 2011.