It's taken 10 years, but professional diver Grahame Knott has finally found a US Air Force plane that crashed into the Channel in 1969. The wreck may help resolve a mystery: did the homesick mechanic who made off with the aircraft from his base in Suffolk lose control - or was he shot down?
"It cost me a fortune in beer," says Grahame Knott, "and I had to filter out a lot of chuff."
A crucial part of his decade of research was spent in pubs along the south coast of England, looking for men who operated trawlers and scallop dredgers.
These boats scrape nets along the seabed and occasionally turn up curious pieces of metal - which is what Knott was buying beer to hear about.
By listening carefully, he could guess whether the objects were likely to have come from aircraft, and if so how old they were, though it was not always easy to know exactly where they had become snagged in the net.
The Channel is littered with wrecks from the two world wars and the fishermen often assumed, incorrectly, that these were what Knott was looking for. But eventually, with the information he acquired, he was able to narrow down his initial 100 sq mile search zone to five target areas in a 30 sq mile patch of sea.
The culmination of this investigative work in snugs and public bars came in March this year, when Knott set out into the Channel to search for the 37-tonne, four-engine Hercules plane that USAF mechanic Paul Meyer had taken off in, singlehandedly and without permission, in 1969.
With fellow members of his Deeper Dorset diving team, he would set out from Weymouth at 04:00 and return home 16 hours later, after a perilous day spent crossing busy shipping lanes in a 13m-long boat. Often they had to dodge enormous container ships as they zig-zagged to-and-fro in one of the search zones.
"We were looking 200m either side with our sonar equipment dragging behind us on a 250m cable, so we cut a 400m swathe," says Knott.
"But our biggest fear was missing a sign of the wreck."
A fully kitted-out recovery boat would have had an easier time of it, Knott acknowledges.
A boat like this would have dynamic positioning devices enabling it to automatically hold its position in strong tides - but it would cost millions to buy and about £30,000 per day to operate.
By contrast Knott's team had a "day vessel", not designed for long-trips, and equipment that cost about £60,000 in total. They crowdfunded to meet their petrol costs of £200 per outing.
On top of that, weather and tides were often unhelpful - in nine months they could only go out 21 times. And it was only on the very last planned search day of the year, in mid-November, that the team finally found something that looked promising.
There was no dramatic Eureka moment, Knott recalls, more of a slow realisation that they had made their longed-for discovery.
First, sonar readings told them they had found an object of interest. They then lowered a video camera to within 2m of it so they could take a look. This confirmed it was aluminium, because of the distinctive way the metal corrodes.
"Then we spotted a wheel sticking out the sand, then a section of wing with rivets, it just got bigger and bigger," says Knott.
This was it, the Hercules that had gone missing on 23 May 1969.
Knott then found himself thinking of the pilot, alone in the cockpit all those years ago.
"The seabed is a lonely place," he says.
In 1969, Sergeant Paul Meyer was a US Air Force mechanic based at RAF Mildenhall in Suffolk.
At 23 he was already a Vietnam veteran and he was deeply unhappy - homesick for his wife and stepchildren and struggling with alcohol. His request to return to a USAF base in Langley, Virginia, had been turned down.
On the fateful night of 22 May 1969 something snapped. He drank heavily at a party and was then arrested for being drunk and disorderly. He was escorted back to his barracks and told to sleep it off.
Instead, using the assumed name "Capt Epstein", Meyer managed to take charge of aircraft 37789, a Hercules transporter C-130.
Having worked as a mechanic on board, he knew the protocols to get access to it, and had some working knowledge of how to fly it.
Alone and still inebriated, he took off on a mission to see his wife. While flying westwards, he was able to speak to her on the phone, a call that was partly recorded.
Meanwhile, military jets were scrambled to track him.
An hour-and-a-half after take-off, radar contact with the plane was lost. A few days later its life raft washed up on the Channel Island of Alderney.
Nearly 50 years later, it remains unclear if he lost control of the plane due to poor weather and his lack of experience as a pilot, or if it was shot down to avert the risk of it crashing into a populated area.
Knott, who admits to having become obsessed with the story, hopes the wreck may finally provide an answer.
The Deeper Dorset diving team have found a few wrecks in the Channel over the years.
In the mid-90s they found the Aracan, a sailing ship from 1874 that had once outrun The Cutty Sark - "quite a sight," Knott recalls.
They were also the first sports divers to locate the wreck of the Miniota, a WW1-era vessel that sank with silver bullion deep in the middle of the Channel, though Knott says it soon became clear that professional salvage divers had been there first, without reporting their find.
Deeper Dorset are not treasure hunters themselves, Knott says.
"We're story hunters who dive wrecks to satisfy our curiosity."
Although Knott also runs a dive charter business, taking paying customers out to see wrecks, he says he won't do that with the Hercules.
"It's not like a typical boat wreck - it's more like a sacred site, especially since Meyer's family are still alive," he says.
Instead the plan is for the Deeper Dorset team to dive down to the wreck site in spring, when the underwater visibility in the Channel will have improved, and to video the wreck from all angles. This will enable a computerised, 3D-image of the crash site to be constructed, and studied by air accident investigators.
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Emma Jane Kirby worked with Grahame Knott this year on a series of reports for the PM programme on BBC Radio 4, and has written two stories:
What Knott has seen so far has already left him puzzling.
"There's a large section of the aircraft that I just can't believe would be as it is, intact, if the plane hit the water at 250 knots, its normal air speed - but I don't want to add more rumour or speculation," he says.
A Hercules plane of the type flown by Meyer can be successfully ditched in water so that it floats, says David Gleave, an independent aviation safety investigator who has followed Knott's progress closely.
It would then sink, but largely keep its shape.
Gleave is especially perplexed by one piece of information in the United States Air Force official accident report from 1969, which says: "The opinion of the investigating officer is that the aircraft impacted the water with such force, immediately followed by explosion and flash fire, that survival of the occupant is most improbable."
An explosion and flash fire are inconsistent with a plane hitting the water, whether the pilot lands it on water deliberately or it falls from the sky, says Gleave. But an explosion and fire would be consistent with a missile hitting the engine of the aeroplane.
The official accident report says that one US fighter plane from RAF Mildenhall was scrambled to catch up with the Hercules but failed to locate it and returned to base. However there's evidence that British and French aircraft also attempted to intercept Meyer - and the accident report makes no mention of them.
"There are many parts of the puzzle still missing," Gleave says.
Knott says that one of the things that has kept him going over the last 10 years is a feeling of personal affinity with Paul Meyer.
"I feel strongly that his story hasn't been told," he says.
"I don't think he was this drunk guy who couldn't fly. In fact I don't think he could have been that drunk to fly for as long as he managed to."
In Knott's eyes, Meyer was a man struggling with family problems and work pressure, suffering from what would be described today as post-traumatic stress disorder.
He was also something of a "Huckleberry Finn" character, who liked to do things his own way - as one military tutor described him.
His body has never been found, though a corpse seen floating near Jersey in July 1969, in what could have been flight gear, was not brought to land and allowed to drift away. Even if the body had remained with the wreckage, Knott thinks none of it would be left today.
Meyer's wife, Jane, now in her 80s, and his step-son, Henry Ayer, have both written to Knott since the discovery of the Hercules.
Ayer is delighted, Knott says, although "it's also bittersweet for him and tinged with sadness".
For the 50th anniversary of the crash, on 23 May, Knott plans to dive down and place a plaque on the wreckage.
He hopes it will be possible for Meyer's family to be there for the ceremony.
Additional reporting by Dougal Shaw
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