Jeremy Clarkson enjoys Darlington's Victoria Falls Bridge

Marvelling it how it was constructed, Clarkson says: “There’s a great big gorge in the way… it doesn’t matter… Here's what we'll do, we will build a bridge in Darlington, ship it out there and assemble it in situ and it will fit – and it did!

“And here it is…”

The three cars approach the bridge on The Grand TourThe Victoria Falls bridge as seen in the programmeThe camera then pans out to reveal the vehicles are travelling 128 metres above the Zambezi River over the Victoria Falls Bridge. The views are so spectacular that, open mouthed, even Clarkson seems lost for words as he goes across the beautiful, single span arch, that defies all gravitational logic to hang almost amid the spray of the falls – of the “thundering smoke” – behind it.

Jeremy Clarkson is left open mouthed by the bridgeBut if he had known the extraordinary way in which the bridge was constructed 120 years ago, he would surely have stopped to recreate the technology – and then send sidekick Hammond uncertainly across a swinging zipwire over the falls.

Businessman and colonialist Cecil Rhodes had a dream of building a railway the length of Africa, from the Cape of Good Hope in the south to Cairo in Egypt in the north, to help the spread of the British Empire. One of the railway’s first major obstacles as it headed north was the Zambezi, which formed the border between Southern Rhodesia (now Zimbabwe) and Northern Rhodesia (now Zambia).

Rhodes was as aware as Clarkson of the dramatic potential of the backdrop and ordered that the bridge should be built close enough to the falls to catch the spray, making it a tourist must-see.

A London engineer, George Andrew Hobson, designed a clever bridge that would expand and lift on its giant hinged bearings as the fierce African sun heated the metalwork.

All the world's construction firms were invited to tender for the contract, but only two did: Dorman Long, of Middlesbrough, and Cleveland Bridge, of Darlington.

The Darlington company, formed in 1877 by Albert Hill steelworkers, won with a £72,000 bid.

On September 2, 1903, the company's chief construction engineer, Georges Imbault, the Frenchman who also designed Middlesbrough's Transporter Bridge, arrived on site.

His first job was to fire a rocket across the 250 metre (820ft) wide gorge.

Attached to the rocket was a string. Attached to the string was a steel wire. Once the wire was secured, he bravely winched himself across in a bosun's chair.

The wire was supposed to be 420ft above the Zambezi, but it sagged alarmingly in the middle. Nevertheless, he made it. The job was begun.

Back at the Cleveland Bridge works in Smithfield Road, Darlington, the steelworkers were making the 1,868-ton bridge in segments.

On March 5, 1904, they despatched the whole lot by train to Middlesbrough where it was loaded onto the SS Cromwell and sailed to Beira in Mozambique. There it was placed on the Mashonaland Railway took it to Bulawayo, and from there it was transported to the southern side of the Zambezi.

It was accompanied by "20 skilled mechanics or erectors, all men of long service with the firm" from Darlington who, for the next year or so, lived in huts on the riverbank. About 400 local workers were recruited to help them grow the bridge out of the rocks on the two sides of the gorge so that, hopefully, they met in the middle.

Men riding across the Zambezi on the electric cableway tested in DarlingtonThis meant all the materials for the construction of the northern side of the bridge – all 40,000 tons of them – had to be carried over the gorge on a giant zipwire, a Brothers' electric cableway. This was an upgrade of Georges Imbault’s steel wire, and it had been put through its paces at Smithfield Road.

Crossing the Zambezi on an electric zipwire from DarlingtonThe Darlington & Stockton Times reported in 1904: "It has just undergone a final and most convincing test at the works in Darlington in the presence of engineering experts from various parts of the country.

"A steel wire rope is suspended between two steel supports, one on each side of the river. An electric conveyor travels along the rope and will transport at each journey ten tons of material."

What looked convincing when erected a few metres above the ground in Darlo cannot have looked so trustworthy when it was dangling 128 metres above the dashing, spuming Victoria Falls. What did those Darlington men think in Africa as they clambered out onto the swinging, nauseating cableway and ventured across the Zambezi?

The Jack Tar engine on the bridge, although first of all it had to cross the gorge on the zipwireAnd one of the first items they had to take across was a 19 ton locomotive, called Jack Tar, made by Manning Wardle and Company of Leeds, which was to work on the northern bank.

Watching these extraordinary scenes unfold was Captain Ernest Harry Lindsell Salmon. He came from a British colonial family and was the Rhodesian government’s transport officer, and his job was to make sure the work was up to scratch.

He was equipped with a camera and when we last told this story more than 12 years ago, we were approached by his granddaughter, Sarah Britton, who lived in Sedgefield and still had his photo-album with these amazing pictures in it.

Capt Salmon's picture of African workers on the Victoria Falls BridgeIt took only nine weeks to erect the steel segments. As they neared the middle, Cleveland Bridge director William Pease, of Mowden Hall, ventured out onto the cableway with the British Boer War hero, Lord Frederick Roberts. In the middle, Mr Pease jokingly threatened to turf his lordship out to his death unless he promised to come to Darlington to unveil the South African War Memorial in St Cuthbert's churchyard. He did.

Captain Salmon's picture showing the two sides growing together. Behind is the spray from the falls. Beneath the bridge is a safety net which caught dropped toolsOn March 31, 1905, as the sun set over the Victoria Falls, the two sides of the bridge met.

Sadly, there was a one-and-three-quarter inch overlap. Jeremy Clarkson was wrong. It didn’t fit.

The engineers returned to their huts in disappointment.

Up early next morning, they discovered the wind had changed direction, blowing spray from the falls onto the steel, cooling it after it had baked the previous day in the African sun, allowing it to contract. Now, the two halves were a snug fit and, at 7am on April 1, they were bolted together.

Then the Darlington erectors waited anxiously for the sun to rise to see if the hinged bearings could cope with the expanding metal.

But of course, they could.

In July, the construction was considered strong enough – perhaps it was even certified by our government safety officer with the camera – for Jack Tar to make its first journey across, pulling two wagons.

The bridge was formally opened on September 13, 1905, by Professor Sir George Darwin, the son of Charles, and now is regarded as one of the great engineering wonders of the world – such a great wonder that it appeared to momentarily leave even Jeremy Clarkson speechless.

Cleveland Bridge's publicity material after it had built the Victoria Falls Bridge

Another of Capt Salmon's pictures showing the bridge under constructionAnd today it looks like this...