“MR Chellin, how many fingers am I holding up?”...

These were the words spoken 50 years ago as an ageing war hero, blinded since the First World War, was given a state-of-the-art procedure at Southend Hospital to restore his sight.

“Two, responded an emotional Frank Chellin. “I can see two fingers.” The 75-year-old former soldier then broke down and wept. For the first time in 50 years he could see clearly again.

Mr Chellin had been under the care of surgeons at Southend for many years. He had been rendered totally blind since he was struck by a mustard gas attack while fighting the Germans on the Western Front in the Great War.

Just a few months before the ‘miracle’ operation to restore his sight completely, Princess Anne had visited the hospital to open a £3.5million extension, and the popular royal had been pictured chatting to Mr Chellin as he told her about the treatment he had received.

At the time of the photograph being taken Mr Chellin had some sight in one of his eyes, thanks to operations performed at the hospital just a few weeks earlier.

A tiny plastic lens had been inserted in his right eye. It enabled him to read, write, watch television and, for the first time, go out alone without his white stick.

But in March of 1972 he was given the chance to undergo a revolutionary operation which would go onto offer hope to millions of blind people all over the world.

For Frank this was another step out of the darkness since the mustard gas attack of 1918. The groundbreaking but dangerous surgery on his right eye was to be performed to fully restore the vision in both of his eyes.

For the eye surgeon who pioneered and perfected the operation in 1972 – known as an “intra-corneal plastic implant” it was the culmination of years of research and experiment.

First a layer of his cornea, the thin film of skin which covers the iris, had to be removed and a cornea – taken from a dead person in the same way as a kidney transplant —stitched in its place

After it was finished, clustered around the bedside in the sunlit ward, doctors and nurses watched silently as the surgeon gently removed the final bandage from Mr Chellin’s eyes.

Holding up two fingers the surgeon said softly: “Mr. Chellin, how many fingers can you see?”

There was a pause. Then Frank’s face lit up with an expression of wonderment. “Two . I can see two!” he said. Then he broke down and wept.

The new “plastic window” technique carried out on Frank led the way for eyesight surgery which would go on to help many blind people in the world, especially those in the Middle and Far East, who were victims of burns.

However, although it worked on Frank, a spokesman for Southend Hospital said at the time that the procedure was still in its infancy

“Patients must not expect miracles every time,” they said.

Frank was one of the lucky ones who finally had his sight restored after such a horrific attack. Mustard gas was the most widely used chemical weapon used during the First World War by the Germans.

It could kill by blistering the lungs and throat if inhaled in large quantities. Its effect on masked soldiers, however, was to produce terrible blisters all over the body as it soaked into their woollen uniforms.

Contaminated uniforms had to be stripped off as fast as possible and washed – an impossible feat for those on the frontline.

The gas got its name from its mustard colour and had an odour reminiscent of garlic or horseradish.

Although the mortality rate from mustard gas was only 2-3 per cent, those who suffered chemical burns often suffered life-limiting respiratory problems and lengthy hospitalisations. Even if they recovered they were at higher risk of developing cancers during later life.

A number of Essex soldiers had their lives blighted by the gas. In July of 1919 a man named Robert Murrells was charged with breaking into a shop in Colchester and stealing £30 worth of silver. The court, however, took pity on him when they heard his story. He had served as a soldier in France where he had been hit by mustard gas. It had rendered him useless and he could no longer use his arm and his chest was terribly affected.

The court heard how “Every employer he had approached had refused to employ a man who was mentally and physically deficient when they could employ an able-bodied soldier. That is why he steals.”

In September 1923 a one time successful boxer and footballer, Harry Palmer from Chelmsford died.

He had been a soldier and served in France and been involved in heavy fighting and was wounded several times.

But he too was also subjected to a German mustard gas attack. When he returned to Chelmsford after the war he worked at Marconi’s wireless factory. But for the last six months of his life he was unable to carry out even the simplest task because of the illness in his lungs caused by the gas attack. He died from abscesses to the lungs and left a young widow.