[VicDakin]

Not content with using the Grim Reaper to push home the message they also had Donald Pleasence as narrator.
"I am the spirit of dark and lonely water: ready to trap the unwary, the showoff, the fool..." intones the voiceover, "...and this is the kind of place you'd expect to find me. But no-one expects to find me here", as the scene switches to a group of children playing on the muddy edge of a murky pool. A boy is teetering on the steep, slippery bank attempting to retrieve a football from the pool with a stick. "But that pool is deep. The boy is showing off...the bank is slippery" says the spirit, approaching from behind as the child slips into the water.
"The unwary ones are easier still" observes the spirit, as a boy is seen fishing in a duckpond, leaning out over the water as he holds onto a tree branch. "The branch is weak, rotten; it'll never take his weight." The branch gives way and the boy tumbles into the pond as the spirit appears among the reeds.

Lonely Water (widely known as The Spirit of Dark and Lonely Water) is a 1973 British Public Information short film made for the Central Office of Information. The film aimed to warn children of the dangers of careless or foolhardy behaviour in the vicinity of water, and was shown regularly on TV for several years during breaks in children's programming. Lonely Water is widely recalled as one of the most memorable and chilling of PIFs. In a poll carried out by the BBC on the 60th anniversary of the COI in 2006, Lonely Water was chosen as the UK's fourth-favourite PIF of all time and the highest ranked one-off production. Dozens of comments attested to the film's power and lasting impact on 1970s children.