11 December 2010 Last updated at 11:02 ET

Officer claims 'I've seen Nessie'

By Paul Dunt BBC Inside Out East

Simon Dinsdale says he saw an "immense object" on Loch Ness 50 years ago

A retired police detective from Essex claims he has seen the Loch Ness monster.

Simon Dinsdale wants to convince others that film shot by his father, Tim, 50 years ago proves Nessie exists.

"I saw this immense, extraordinary object, it looked like the back of a huge animal," he said.

"It stood two or three feet (0.6m to 0.9m) out of the water, four or five feet (1.2m to 1.5m) across, reddish brown and had a blotch on the left flank which I could see very clearly.

"And then it started to move - a most electrifying moment."

The RAF analysed the film and concluded it was not a boat or submarine, but an unknown animate object, he said.

Mr Dinsdale added: "I'm experienced at looking at evidence and I can tell you that on the balance of probabilities there is something large and unknown living in this loch."

The full report can be seen on Inside Out (East) on BBC One at 1930 GMT on Monday 13 December 2010