To the Italians Mensun Bound has always been a hero.
His underwater exploits, hunting for wrecks in the Mediterranean, culminated in the excavation of a 2,500-year-old Etruscan vessel off the island of Giglio in the bubbling cone of a live underwater volcano.
But for all the artefacts from the Greek and Etruscan worlds (including pottery, painted animals and human figures) that he brought to the surface, the Oxford University archaeologist always felt the Ancient wreck was robbed of its crowning glory.
For soon after the 1961 discovery of the ill-fated trading vessel by Englishman Reg Vallintine, a German sports diver spotted what he first took to be a cannon ball. When Hans Gradl picked it up he saw it was a helmet, which he showed to Vallintine who made a hasty sketch.
But the German later managed to leave the island with the exquisitely engraved soldier’s helmet dating from 600BC, and shaped from a single piece of bronze.
From the time that Mr Bound arrived in Giglio to lead the excavation of the wreck 30 years ago, the lost helmet has come to obsess him and he has been pursuing it across Europe ever since.
He was to find it in Germany in 1982 when he traced the diver by telephoning everybody of the same name in the German telephone books. Because of its high value, put at millions of pounds, it was being kept in a bank by Gradl.
Mr Bound, nevertheless, persuaded him to see the helmet, having satisfied Gradl that he was a serious Oxford academic. He photographed it, made drawings and even wore it. But it was to be the last time the helmet was ever seen.
With a museum built on the island of Giglio to house artefacts from the famous wreck, and the 50th anniversary of its discovery approaching, the Italians have turned to Mr Bound to head an international appeal to locate the helmet.
For the Falkland Islands-born diver — who has brought up an eagle insignia and guns from the German pocket battleship Graf Spee, salvaged statues from a sunken Roman galley and raised a cannon from Nelson’s first ship — it represents one of the biggest challenges of his career.
The trading vessel sank off Italy en route to the Greek colonies and Mr Bound led the excavation over five fruitful years in the 1980s, assisted by his wife and colleague Joanna Yellowlees. The results of their work fill the entire floor of the Underwater Archaeological Museum at Port Santo Stefano, on the peninsula opposite Giglio.
Mr Bound, 59, a research fellow at St Peter’s College, said: “It is hoped that the new museum will one day become a permanent home for the helmet, which is the most spectacular item ever to have come from the island and one of the most important archaeological finds ever made in Italy.
“If the helmet could be recovered it would undoubtedly become an emblem for the island.”
To mark the beginning of the search, a bronze replica has been unveiled in the Castle of Giglio, the spiritual heart of the island.
For Mr Bound, who lives in Horspath, it is unique.
“I have seen all the Greek helmets in existence, and this is by far the most beautiful. It is even more important because it comes from a known archaeological site of the very early 6th century BC. Beaten from a single sheet of bronze and decorated with snakes and wild boars, there is nothing else like it in the world. It is a masterpiece of ancient art and technology that could not be duplicated by a modern craftsman.”
He well recalls trying it on. “Suddenly I felt myself transposed across the millennia, As I looked out from its eyes I wondered what was the last thing that soldier saw when he put it on? Who was he, what was he thinking?
“Sometimes when you immerse yourself in antiquity, there are moments when something from it just seems to reach out and touch you on the shoulder. That is what happened that day in a suburb of Hamburg.”
He was surprised by its close fit and comfort.
“I had imagined that it would be unstable and that the vision would be very restricted but not at all. Movement was unimpaired and because the almond-shaped eye curved around the sides of the helmet, vision was completely unrestricted.
“It has always been a dream of mine to see it back where it belongs on the island. Sadly, Gradl has died and all efforts to trace his family have so far failed.”
Eight years ago, Mr Bound was contacted by dealers seeking his assistance in the authentication of a helmet that had arrived in Switzerland from Germany. But it was never to go to auction. Before he could fly over, the helmet had been sold in a private sale.
Mr Bound suspects that the helmet is now in a private collection. The initial challenge is to find the owner before negotiations with the Italian authorities may begin.
The mayor of Giglio, Sergio Ortelli said: “What I would like is to talk to whoever has the helmet, and in the spirit of friendship, and on behalf of the people of Giglio, to ask for it back.
“And also to invite to Giglio, whoever has it, as our guest of honour, for a special ceremony at the new museum to mark the return of our island’s lost treasure.”
For the man who has spent much of his life discovering shipwrecks, his greatest find could still lie ahead of him — without even having to put a foot in water.
But for once the outcome is really out of Mr Bound’s own hands.