The incredible story of a Chesterfield diver's mission to save his friend trapped at the bottom of the North Sea without oxygen

At the bottom of the North Sea, Chesterfield deep sea diver Duncan Allcock was swept up in the unimaginable when an accident left his friend and colleague with just five minutes of air- and rescue was more than 30 minutes away.

Now the terrifying ordeal, and subsequent rescue mission, has been re-told in blockbuster documentary Last Breath- offering a glimpse into the fascinating, claustrophobic and mysterious life of a saturation diver.

The nightmare unfolded on September 18 2012, 127 miles east of Aberdeen, essentially ‘right out in the middle’ of the North Sea.

But despite rough weather, it was a standard job for veteran diver Duncan.

“My first inspirations for diving was watching Jacques Cousteau and thinking- that’s what I want to do,” he said.

“Visiting coral reefs, swimming along with all the animals. It looked absolutely superb. It was a dream for me to be a diver and go under the sea.

“Now, the North Sea is definitely one of the most dangerous environments in the world.

“The water temperature is four degrees on the seabed, which is a killer. But it’s nothing I hadn’t done before."

Co-diver Chris Lemons was 18 months into his post as a commercial saturation diver in the offshore oil and gas industry.

It was an exciting time in his life. He was engaged to be married and building a house in the highlands with his fiancée, Morga Martin.

'On the seabed, cold, pitch black and silent. Can you imagine?'

'On the seabed, cold, pitch black and silent. Can you imagine?'

That day he was be working with Duncan, who had become a mentor and ‘bit of a father figure’ to the then 33-year-old, and another experienced diver, Dave Yuasa.

Duncan was manning the ‘diving bell’, which was attached to the Bibby Topaz support vessel on the surface, while Dave and Chris dived down to perform maintenance work on an oil well.

Duncan said: “When you’re lifting the helmet onto the diver’s head, you look into their eyes. You can see if they’re happy or frightened out of their wits.

“At no point that evening was Chris anxious. He was raring to go. He wanted to prove that he was as good as everyone else.”

The film offers a fascinating glimpse into the life of a saturation diver.

The film offers a fascinating glimpse into the life of a saturation diver.

When the alarm sounded, the maintenance work was well underway by Dave and Chris.

What they didn’t realise was that the positioning system had failed and 100 metres above the Bibby was now drifting out of control, away from the dive site. The emergency status was on red.

Dive supervisor Craig Frederick immediately instructed his divers to return back to Duncan and the safety of the bell.

As always Dave and Chris were attached to the bell by their ‘umbilicals’ — long intertwined cables and hoses that carry breathing gases, hot water to combat the frigid North Sea, power to the divers’ headlamps and communications to the ship.

When working, the umbilical is ‘literally a diver’s lifeline’. But as the ship drifted further away from the dive site, everything attached to the vessel began being dragged along with it.

Everything except for Chris. His umbilical was snagged on the structure he and Dave were working on.

Duncan (pictured), Chris and Dave all appear in the film and offer a first-hand account of the ordeal.

Duncan (pictured), Chris and Dave all appear in the film and offer a first-hand account of the ordeal.

As the full weight of the 8,000 tonne ship strained against his lifeline, his umbilical started to stretch.

Seeing what was happening, Dave desperately tried to get back to Chris to try and free him.

He nearly made it, but just as the two men came face-to-face they hear a loud tearing noise followed by a deafening bang.

Chris’s umbilical had snapped and Dave was dragged backwards, away from Chris and off the structure.

As Dave climbed back to the safety of the bell, Duncan was pulling in Chris’s umbilical.

As his bell was pulled dangerously through the hazardous deep, Duncan’s own life was in very real danger.

Being tipped over at a dangerous angle his bubble of air could easily be lost, along with his life, at any moment.

Yet even as he clinged to the walls, his thoughts were with saving his protégé.

“I was hoping I was pulling Chris in, but in my heart of hearts I knew I wasn’t. I knew there was nothing on the end,” he said.

“The hot water hose came in first, broken and tattered at the end.

“Then I had another couple of wraps of umbilical before the broken end of his gas hose came in, which was making quite an immense noise.

“I put my hand on the regulator to turn it off. You never, ever turn off a diver’s gas while he’s in the water. It’s tantamount to killing him.

“I felt like I had let Chris down- that was his only lifeline to the bell.

“I could have cried at that point. I didn’t know whether to be sick or cry. I just shouted, I’ve lost my diver. I’ve lost my diver.”

With access to only five minutes of back-up gas, the crew knew Chris had a minimal chance of survival.

“I knew Chris. I knew Morag,” said Duncan. “I wondered how I was going to tell her we went on a dive and he never came back.”

What unfolded next was a frantic rush against the clock to regain the control of the ship and to find Chris at the bottom of the sea.

It would take over half an hour to get back to the structure, so the team prepared themselves for what they imagined would be a body recovery.

Directors Alex Parkinson and Richard de Costa made the decision to include harrowing ROV footage of Chris’s body twitching on the structure.

Somehow, and he says he’ll ‘never know how’, Chris survived long enough without air for crews on the surface to get the Bibby back in place and locate him on top of the oil well.

He was hauled safely back onto the bell where Duncan performed CPR.

“I gave him two deep breaths,” said Duncan. “Then I knew we’d got him. He was gonna live. I was just so elated.

“At that point I didn’t know if he’d have brain damage, if he was going to be the same Chris, I just knew he was breathing. He was alive.”

Though he has several theories that are touched upon in the film, how Chris survived on the seabed for half an hour without oxygen still remains a mystery.

“What you have to remember as well as suffering extreme cold and his air tank running out, Chris will have been in the pitch black as well,” said Duncan.

“And on the seabed, it’s silent. Can you imagine that? I’m not a religious person but if there is such a thing as a miracle it’s a miracle that Chris is still with us.”

Thanks to the courage and quick-thinking from all members of the crew and diving team, all three brave men have lived to tell the tale.

Last Breath has allowed them to share their chilling experience with the world.

Director Alex Parkinson: “The film is essentially a thriller, but it also explores evolving fears of our relationship with technology, and how computers and algorithms are taking over more and more control of our lives.

“Last Breath is a cautionary tale of what happens when these systems fail.

“The crew of the Topaz relied on the sophisticated computers to control the ship, but when one errant line of code tripped out all ten levels of redundancy, they found themselves in a situation totally outside their control and where every decision made was life or death.”

Last Breath, which is in cinemas and on demand from tomorrow (April 5).

More information is available at: https://www.lastbreathdoc.co.uk/

The bibby support vessel.

The bibby support vessel.

Real harrowing footage of the rescue mission is used in the documentary.

Real harrowing footage of the rescue mission is used in the documentary.

Duncan Allcock today.

Duncan Allcock today.