A documentary opens this week telling the true story of how a diver became stranded at the bottom of the North Sea after losing his lifeline to air, heat and communications.

In September 2012, Chris Lemons’ umbilical, his vital link to his dive bell, became severed and he was trapped on the seabed for nearly 40 minutes, with his back-up gas tank only holding five minutes of breathable air.

“Last Breath” a documentary coming to UK cinemas this week, tells the incredible tale of his rescue and survival, despite almost non-existent chances of successful recovery.

Chris said: “I realised very quickly that my chances of survival or being rescued were pretty much non-existent.

“You do the quick maths in the moment and I knew that the bailout would only last five or six minutes at absolute best, so I knew that even if they had been straight above me on their way to rescue me there was a decent chance that I wouldn’t have been back in time.

“Once I had resigned myself to the fact that I wasn’t going to be able to save myself, calm comes over you I think, resignation more than anything else.