Image caption The mechanic on the left, working on this S.80 in Cairo in 1914, is thought to be Gus Smith

When an early British sea plane, the S.80, made a three-month expedition south down the Nile in 1914, the mechanic was unnamed in the newspaper reports. But the adventure's success depended on his expertise.

It started with a tweet.

Diplomacy and Twitter might seem like chalk and cheese, but one of my more interesting follows is Tom Fletcher, Britain's ambassador to Lebanon.

Recently Tom tweeted that his great-grandfather Gus Smith had been the mechanic on the first flight along the River Nile, exactly one hundred years ago.

I wondered if he had any more detail. Thanks to family records supplied by Tom's father Mark, which have never before been made public, details of a remarkable adventure emerge.

In the early years of aviation, it was the pilots' skill which caught the public imagination.

The Wright brothers came first in 1903 - a few seconds aloft, at barely more than head height above the ground. Then Louis Bleriot successfully flew the English Channel.

Image caption Gus Smith and Lily Powell married on 6 March 1915

When Frank McClean, a wealthy Irish aviator, steered a biplane he'd developed with the engineering firm Short Brothers between the towers of Tower Bridge in London, the Times newspaper noted: "The engine ran smoothly and the machine was always under complete control."

But the Times made no mention of the reason for such smoothness - McClean's mechanic, a young man named Augustus Leonard Smith - Tom Fletcher's great-grandfather Gus.

Gus had joined Short Brothers just as they were transitioning their aviation manufacturing business from balloons to powered aircraft, backed by lucrative deals with McClean and other pioneers.

Gus quickly rose to the peak of his trade, working at Short Brothers' Eastchurch factory in Kent on some of the era's most technologically advanced flying machines.

By 1913 the Short brothers, under commission from Frank McClean, had developed a "hydro-aeroplane" that could not only take off and land on water, but also carry three passengers.

The French National Air League had just issued a challenge to test the viability of long-distance air travel by flying from Paris to Cairo. French aviators were racing each other that autumn across Europe. No doubt the Brits wanted to go one better.

Amid the Edwardian craze for pharaonic discovery, McClean decided to follow the Nile south.

Image caption The S.80 making history on the Nile

The last week of December 1913 saw McClean, another pioneer aviator Alec Ogilvie, businessman Horace Short and flight mechanic Gus Smith at the Naval Dockyard in Alexandria, on Egypt's Mediterranean coast, receiving a consignment of crates newly arrived from Liverpool containing the disassembled "hydro-aeroplane".

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As flight mechanic, Gus would probably have rebuilt the aircraft himself, from its 20-metre wings to the French-designed 14-cylinder engine. Lives depended on him.

On 3 January 1914, with passengers and crew aboard, McClean steered the extraordinarily flimsy machine of wood and wire into the skies over Alexandria. The Times was there, again noting the pilot but leaving his mechanic unnamed.

With the plane's limited range, the journey south formed a series of short hops. Petrol supplies had been left at points all along the route, but even so the team was plagued by engine trouble.

Image caption The crew relaxed pre-flight with a camel ride at the Pyramids on 24 Dec 1913

Thirteen breakdowns, with extended delays waiting for delivery of spare parts, meant that the flight to Khartoum - perhaps 1,500 miles, at an altitude of around 60 metres above the Nile - took almost three months.

Adding insult to injury, they were overtaken by French airman Marc Pourpe.

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By flying a wheeled monoplane Pourpe didn't have to rely on the meandering river for takeoffs and landings. He made Khartoum in around 10 days.

That said, there doesn't seem to have been any question of a race, and the Brits persevered, reaching Khartoum on 22 March 1914 - though the prospect of a three-month return no doubt prompted the decision to dismantle the plane and ship it back to England.

Both McClean and Gus Smith flew with the Royal Naval Air Service in the First World War.

Image caption Smith (left) and aviator Alec Ogilvie mid-flight

McClean was knighted in 1926. And Gus's love of aircraft persisted - he worked as a flight instructor between the wars, and died in 1942, at the age of only 58.

A few days later, his sister received a letter on the stationery of London's Royal Aero Club.

It read: "Though it is a long time since my days at Eastchurch and on the Nile, Gus was so much a part of those days and of the struggle to make machines fly that no recollection is complete without him, and it was in great part due to him that failure was avoided."

The letter was signed FK McClean.

This year, Gus Smith's great-grandson Ambassador Tom Fletcher tells me, plans are afoot to commemorate the centenary of the Nile flight with an event in Cairo, where a model of the 1914 plane is on museum display.

I hope they're realised.

For all the headline-making skill of those at the controls, we now, as then, only stay up thanks to the likes of Gus Smith.

There is more information on the 1914 Nile flight at the Royal Aero Club Collection

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