Lighting up the famous Iron Bridge

Searchlights, cameras, action . . . tonight Shropshire's iconic Iron Bridge will take centre stage as it is transformed in a dazzling display of high-powered lights.

The spectacle has become one of the highlights of The Ironbridge Gorge World Heritage Festival, with thousands of visitors seeing the familiar landmark literally in a whole new light.

Organisers are promising something even more spectacular this evening to mark 25 years of the Gorge's World Heritage status.

But even though the scene may have the appearance of a strangely familiar wonderland, it doesn't all happen by magic and chance.

Behind the scenes, in the countdown to a display which will also transform Ironbridge's iconic cooling towers, the wharfage and museum buildings, there have been months of careful planning and choreography, tests and site visits.

Even clearance from the Civil Aviation Authority has had to be granted, as some light beams are so powerful they can strike over-flying aircraft and dazzle pilots.

The man pulling all the strings – not to mention the whopping 4km of electric cabling – is Stuart Roberts from leading light display team EMF Technology. His resume reads like a what's-what of high-profile, star-studded bashes.

At the UK premiere of the last Harry Potter movie in London, EMF were called upon to add their own touch of magic to the red carpet with sensational flame effects lining the route to Leicester Square.

The lighting team also added pizzazz to England's 2018 World Cup bid, delivering a massive outdoor video projection beneath the arch at Wembley Stadium.

And when Manchester City launched its new football kit, its mega-rich bosses turned to EMF to light up the City of Manchester Stadium with a 7kW building projection that set the scene for the unveiling of the strip modelled by Manchester's famous son, Liam Gallagher.

Tonight's display is the culmination of four months of careful planning to ensure everything is alright on the night.

Stuart Roberts, one of a six-strong crew, says: "As the bridge is the main central focal point we are supplying two large-format 8kW space cannon searchlights creating large moving beams into the night sky and pre-programmed projecting beams towards the museum as well as creating large beam effects from the firework display smoke.

"For the bridge area we are providing LED colour-changing lights to light the underside of the bridge superstructure and west façade of the bridge, with the effect of slowly changing the colour of the bridge throughout the evening.

"These are used with permission from the Civil Aviation Authority as there is no other searchlight with such high power – the beams are so powerful that they can hit aircraft in the sky.

"Pilots are given a Notification To Airmen and they will be aware of searchlights operating below from this. If we had not applied for clearance we could be fined £5,000 or be imprisoned!"

Down at the Museum of the Gorge, technicians will colour-wash the structure using environmentally-friendly, colour-changing LED lights. Compared to some of the higher-powered lights elsewhere, some of these consume only an amount of power that would be used to boil a kettle.

There will also be 25-year celebratory projections on to the doors, and two further high-powered searchlights will highlight the bridge and museum.

And opposite the wharfage and along the wharfage, there will be special effects projections of the 25-year celebration of World Heritage Site status, using large scale 7kW slide projectors which produce 80,000 lumens of light power to project massive images of up to 50 metres in size onto the tree line opposite the wharfage.

The wharfage between the bridge and museum will be will be lit with 14 high-powered static coloured floodlights, evenly positioned and projecting upon the tree-line opposite in blue, red, pink and green colours.

And, says Stuart: "The power station has kindly agreed to give permissions to EMF to project a massive image on to the tower, visible from Iron Bridge for the celebration."

As you might expect, watching the results of four months' work and seeing the reactions from visitors is as exciting as being the one who lights the touchpaper on bonfire night.

"It is always enjoyable working with the Ironbridge team," says Stuart.

"To make this annual event successful there is an enormous amount of logistics involved ensuring that the World Heritage Site is transformed for the event, with permissions from the World Heritage Site and CAA to ensure we are keeping within the requirements stipulated for such a special area."

This is the team that has lit up buildings, mountains, statues and even water features. Stuart gets to see the world and light it up.

His trickiest – and perhaps most dangerous – lighting mission was illuminating Table Mountain in South Africa for the launch of the World Cup 2010.

"That was a huge projection requiring ten 7kW projectors, the most powerful kind in the world, and it was a "guerilla" project – no permission – for The Sun newspaper.

"It caused an international incident because the mountain is sacred and to project images on to it is sacrilege. We were in a situation where we had to sign a disclaimer that said we would not do it again. If we did, they would imprison us and confiscate all the equipment."

There will be no such problems tonight . . .