Nessie hunters found a monster while scouring the mysterious Scottish lake – but not of the kind they were looking for.

A robot that was scanning the water and looking for the long sought after monster just found a model of it, sunk at the bottom of the lake.

The 30-foot long model is thought to have got there when it was disposed of after the film The Private Life Of Sherlock Holmes, directed by Billy Wilder, was finished. When the film completed shooting, the team took parts off the model including its humps and sunk it to the bottom of the lake to get rid of it.

A spokesman for VisitScotland, which is supporting the project, said: "Operation Groundtruth has uncovered a recognisable creature.

"Although it is the shape of Nessie, it is not the remains of the monster that has mystified the world for 80 years, but a star of the silver screen."

The discovery partly reflects the plot of the original film, which starred Christopher Lee and included a monster that turned out to be a hidden naval submarine.

The hunt for the Loch Ness Monster Show all 8 1 /8 The hunt for the Loch Ness Monster The hunt for the Loch Ness Monster Searching for Nessie This famous photograph of the Loch Ness monster, allegedly taken on 19 April 1934 by Colonel Robert Wilson, was exposed as a hoax only in 1994 KEYSTONE/GETTY The hunt for the Loch Ness Monster Searching for Nessie Members of the Mirich Film Company scanning Loch Ness for the monster in 1969. The company were shooting 'The Private Life of Sherlock Holmes' beside the loch at the time Getty Images The hunt for the Loch Ness Monster Searching for Nessie The headquarters of the Loch Ness Monster Investigation Team at the side of Loch Ness in 1969 Getty Images The hunt for the Loch Ness Monster Searching for Nessie One of the members of the Loch Ness Monster Investigation Team keeping a watch on the surface of Loch Ness in 1969 Getty Images The hunt for the Loch Ness Monster Searching for Nessie A submarine is lowered into Loch Ness to begin its search for the monster in 1969 Getty Images The hunt for the Loch Ness Monster Searching for Nessie A group of monks from the Fort Augustus Abbey on Loch Ness in 1935. References to a monster in Loch Ness date back to St Columba's biography, 565 AD, where Adamnan describes St Columba preventing a creature in the Loch eating a man. More than 1,000 people claim to have seen 'Nessie' and the area is a popular tourist attraction Getty Images The hunt for the Loch Ness Monster Searching for Nessie An image from Apple Maps in April 2014, which has been interpreted as the Loch Ness monster in the Scottish Highlands Apple Maps The hunt for the Loch Ness Monster Searching for Nessie A model of the Loch Ness monster stands outside a visitor centre in Scotland Getty Images

The model was found on the loch bed during a pioneering survey of the huge stretch of water – which some had hoped would find the real creature.

But the survey appears just to have dampened those hopes that a monster would be found. It has revealed that the “Nessie trench” that believers had argued existed at the northern basin of the loch – and could be hiding the monster – doesn’t actually exist.

The survey is being conducted by a robot called Munin, which is able to swim around and explore parts of the bed that have never been looked at before.

The sunken film star joins a huge set of discoveries already found at the bottom of Loch Ness. They’ve also included a crashed Second World War bomber and parts of John Cobb's speed record attempt craft Crusader, which crashed at more than 200mph in 1952.

The survey - the first of its kind in Scotland - is being carried out over two weeks by Kongsberg Maritime and supported by the LochNess Project and VisitScotland.

Loch Ness has been notoriously difficult to survey in the past due to its depth and steeply sloping side walls.

Munin can map vast areas to depths of 4,921ft (1,500m) and has been used in the past to search for downed aircraft and sunken vessels.

Loch Ness project leader Adrian Shine said: "Because Munin can dive and navigate itself safely at great depth, it can approach features of interest and image them at extremely high resolution.

"We already have superb images of the hitherto difficult side wall topography and look forward to discovering artefacts symbolic of the human history of the area."

Despite no conclusive evidence of the famed monster, the mystery and interest surrounding Nessie is worth an estimated £60 million to the Scottish economy, with hundreds of thousands of visitors travelling to Loch Ness every year in the hope of catching a glimpse.

VisitScotland chief executive Malcolm Roughead said: "We are excited to see the findings from this in-depth survey by Kongsberg, but no matter how state-of-the-art the equipment is, and no matter what it reveals, there will always be a sense of mystery and the unknown around what really lies beneath Loch Ness."