Steve Feltham, 51, from Wimborne, Dorset quit his job fitting security cameras to spend his days living on the banks of Loch Ness, Inverness-shire, in 1991. He became obsessed with the legend of Nessie after a family holiday to the Highlands when he was seven and made it his life's mission to prove she exists.
But after 23 years of patiently watching the loch, Mr Feltham still does not have any proof of the beast's existence - because he forgot his camera the day he did spot the monster in 1993.
He said: "Gutted is an understatement. It was the moment I'd always dreamed of since I was a young boy - but I didn't catch it on film. Ever since I have dedicated my life to seeing Nessie again - and this time I'll be ready with my camera."
Mr Feltham could not believe his eyes when he caught a glimpse of Nessie after just 18 months of living on the banks of Loch Ness.
He said: "I was sitting on the shore near the Fort Augustus end of the Loch when something went past the bay, through the water. It was like a torpedo shot and it had some weight behind it, hitting through the waves.
"Nothing in Loch Ness could create a disturbance like that apart from Nessie.
"I just sat there in amazement. It was the moment I had always been waiting for and I am kicking myself for not taking a photo.
"Since then I have been by the loch with my camera poised, every day, come rain or shine. I won't let an opportunity like that pass me by again."
In 1991, he bought an old mobile library for £1500 and has been living in it ever since, parked in the car park of a pub called the Dore Inn.
He makes models of Nessie to sustain his simple lifestyle, selling them to tourists during the summer months.
He said: "This is my passion and exactly what I want to do with my life. I am hopeful I will see Nessie again, and I will be here ready with my camera every day until that day comes."
"I am living out my dream as a full-time Nessie hunter."