The boy who vanished: 50 years on from the disappearance of Sandy Davidson

On a warm April day in 1976 three-year-old Sandy Davidson was playing with his sister Donna in the garden of his grandparents house in Irvine, when the family dog bounded out to the street.

Sandy chased after the pet while Donna told her grandparents what had happened before also going out onto the street. By then Sandy was gone - and has never been seen since.

Over the years there have been several theories about what happened, from falling into the nearby Annick River to being taken away by a man delivering leaflets.

Donna has now launched an appeal to mark the 50th anniversary of the disappearance in the hope someone can shed some light on the case.

In a statement released through Police Scotland, Donna - who was two at the time her brother disappeared - said it was "beyond heartbreaking" to still not have any answers about what happened on 23 April 1976.

In 2017 she told BBC Scotland News she suspected Sandy was no longer alive.

She recalled: "We were in the garden playing with the dog and the dog got out of the garden.

"Sandy followed the dog and I went after them as well. I returned back with the dog and Sandy has never been seen since.

"It has always been part of my life. It has always been there."

A massive police search was launched at the time, while work on homes and a school for the nearby Bourtreehill estate was suspended. Despite those efforts, no sign of the child was ever found.

Sandy's parents Margaret and Phillip believed that their son had been taken by a lonely man who wanted a child of his own.

That theory gained credence over a decade ago when a workman from the building site contacted Donna after she made an appeal in a local newspaper.

Ms Davidson said in 2017: "He said he saw Sandy going away and holding a gentleman's hand but he didn't feel any cause for concern because he wasn't struggling and seemed quite happy.

"It has played in his mind all this time because he was probably the last person to see him alive. It has affected so many people."

The primary school being built at the time of the disappearance was demolished in 2014, but despite Donna and her family's pleas the land was not fully excavated.

Occasionally the family have been given hope, only for it to be quashed. In November 2013, someone born around the same time as Sandy came forward and underwent a DNA test. However it only proved he was not Sandy.

Two years later, someone contacted Donna through a missing persons support Facebook group, alleging they were abducted by a teenage girl around the time of the disappearance. Police were not able to link the incidents.