Netherby Deep: The tragic drowning that tainted a Yorkshire beauty spot

"Avoid this place as you would a plague."

Over 50 years old, with faded lettering and covered in moss, it stands just downstream of Harewood Bridge, close to the village of Kearby with Netherby, and was erected after a tragedy which tainted a popular holiday spot forever.

Scaleber Force: The Yorkshire waterfall that's off the beaten trackIn the 1930s, long before cheap foreign travel and mass car ownership, it was difficult for poor city families to visit the coast. An alternative day out was the natural 'beaches' that formed on the banks of the Wharfe, from where children could swim in the shallow, meandering sections of the river.

One of these spots was called Kearby Sands, and could be easily reached from Leeds. Sand had been brought from the beaches of Bridlington to create an artificial bay, chalets were built and a caravan park and pub opened to serve the daytrippers. On busy summer days in the 1950s, hundreds of people would visit Kearby Sands.

Could Downton Abbey filming and the story of Princess Mary spark a visitor boom at Harewood House?One day in June 1963, the Nicholson family, from Tilbury Terrace in Holbeck - an inner-city, industrial area of Leeds - turned up at the Sands. Their eight-year-old twins, Andrew and Stewart, played happily in the river, while their parents sunbathed. They were last seen by the water's edge before the alarm was raised when they suddenly disappeared.

The boys had drowned in a notorious danger zone known as Netherby Deep. Although it appears calm and tranquil, beneath the surface the Deep is treacherous; there are whirlpools, strong currents and a sudden 30ft drop onto a sandbank. Police divers found the twins' bodies 25ft underwater.

Warning signs that had been erected had been removed by vandals.

Gordale Scar: The Yorkshire ravine that was the inspiration for Helm's Deep in Lord of the RingsLessons were learnt from the tragedy - a member of a local swimming club offered to act as lifeguard on busy summer Sundays, and eight more children were rescued that season.

The boys' grandfather, Arthur Chapman, replaced the vandalised signs with one of his own, which remains there to this day and displays an unsettling and chilling message.

"This notice was erected by the grandfather of eight-year-old twin boys who lost their lives here. They were last seen by the water edge. Five hundred people were here but nobody saw a thing. If you care for your children please take them away. Avoid this place as you would a plague. It could happen to you."

Kearby Sands declined in popularity as a holiday destination after the drowning, although other factors, such as the rise of foreign package tours, also had an impact. The chalets were gradually removed, and the Sands themselves became overgrown and difficult to access. Today, there are few traces of Kearby's heyday, when 500 people could gather on the banks - but see nothing.