One night a few years ago sonar equipment registered two large moving objects in the peaty waters of Loch Ness. Simultaneously an underwater camera photographed two shapes which, when computer enhanced, looked like animal fins. In 1975 two more pictures were published.
In this documentary Hugh Burnett looks at some of the evidence, eye-witness accounts and opinions which suggest that Loch Ness is either the world's most amazing natural aquarium or just another Scottish loch haunted by the legend of the water horse.
Producers PETER BALE, HUGH BURNETT