The blue-eyed and blonde-haired three-year-old vanished on 23 April 1976 and has never been seen or heard from since.
Police Scotland has issued a fresh appeal for information and has released an image of what he may look like today.
Sandy's younger sister, Donna Davidson, has continually campaigned over the years as part of efforts to solve the mystery and is urging anyone with knowledge of what happened to come forward.
She said: "It is hard after 50 years and distressing that I still don't know what happened to my brother.
"To have no answers to what seems like a thousand questions is beyond heartbreaking.
"Sandy is very much in my thoughts and as a family we are urging anyone who can help to get in touch."
Sandy had been playing in the garden of his grandmother's house in the Bourtreehill area of Irvine along with Donna, then aged two, and the family dog.
It is thought the toddler may have left the garden to follow the pet dog.
Extensive searches were carried out, and over the past five decades there have been multiple appeals and high-profile media campaigns, but to date there has been no trace of him.
The case was even featured on an episode of TV series Missing Children: Lorraine Kelly Investigates back in 2009.
The new Police Scotland image was prepared by the force's forensic services.
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Detective Inspector Louise White said: "Sandy remains a missing person and our thoughts are very much with his family on this momentous anniversary of his disappearance.
"It is a very hard time for them.
"Someone must have seen Sandy that day and the answers his family need are out there somewhere. Someone must know something and I would urge them to contact us.
"Even the smallest piece of information could help us find out what happened to Sandy so please get in touch if you can assist.
"Anything new will be thoroughly assessed so contact us on 101 if you have anything to tell us, no matter how insignificant you might think your information is."
A picture of a grinning Louis, leaning with his arms folded, in a blue textured quarter-zip style jumper, was posted to Instagram on Thursday.
The caption read: "Happy birthday, Louis! 8 today!" followed by a red balloon emoji.
William and Kate's youngest, Louis is known for his cheeky nature.
The picture was taken earlier this month by photographer Matt Porteous, to whom the Waleses often turn to mark family occasions.
Janet Fordham, 69, suffered fatal injuries in the collision on 14 February 2023 after coming to the country to marry a Ghanaian man she met online, who claimed he could help her get the money back.
Mrs Fordham had fallen victim to several online scams during a five-year period that saw her lose her home and life savings, estimated to be up to £1m, Devon Coroner's Court heard.
When she travelled to Ghana, the retired housekeeper was living in a caravan at the home of her son, Martin, and daughter-in-law, Melanie Fordham, in Honiton, Devon.
She started using online dating websites in 2017 and met a man who claimed to be a British Army sergeant major working in Syria and needed her help to get gold bars to the UK.
Mrs Fordham told her family that they were in love and that he was retiring to return to the UK, with the couple wanting to buy a house together, her daughter-in-law said, adding that she warned her the man would be asking for money.
Melanie Fordham added: "I told her categorically not to send him any. Janet had been sending money to him, but we didn't find out about this until years later. I believe she gave him around £150,000."
Mrs Fordham later learned she had been defrauded again by a "diplomat" after her UK bank accounts were frozen, but her family said they don't know how she transitioned from one fraud to the next.
Melanie Fordham said her mother-in-law "transferred money by several means, including bank transfers, wire transfers at the post office, and potentially a travel agent", but the banks and post office stopped her mother-in-law from using their services because they recognised it was fraud.
Third man promised to help recover funds
The inquest heard another man, named Kofi, contacted Mrs Fordham, claiming he was a doctor in Ghana who worked part-time at a friend's mobile phone repair shop, where he supposedly found a phone containing messages to and from Mrs Fordham.
Kofi claimed he contacted Mrs Fordham because he believed she had been scammed and wanted to help get her money back, Melanie Fordham said.
Police spoke to Mrs Fordham about Kofi, but officers could not further the investigation as she failed to respond.
Detective Sergeant Ben Smith, of Devon and Cornwall Police, said officers contacted Mrs Fordham about allegations of fraud in 2017, 2020 and 2022 and tried to persuade her "not to have any contact with the criminals and not to hand over money", but she was making these decisions of her own free will.
Mrs Fordham continued to transfer money abroad using Bitcoin and ATMs, causing her daughter-in-law to contact the police again.
"Whether she was in so deep, she couldn't accept it was all gone, she had to keep piling money in the hope of getting something back," Melanie Fordham said.
"Whether she genuinely believed what she was being told, we will never know."
Apart from using her savings and home, Mrs Fordham also borrowed money from other family members, totalling around £140,000, was in arrears on loans and credit cards and even cashed in her pension, withdrawing the maximum £500 a day.
Flying to Ghana for marriage
In October 2022, Mrs Fordham flew to Ghana to meet Kofi, with whom she was romantically linked.
"As a family, we tried everything to stop her, but she was adamant," Melanie Fordham said. "I spoke to her doctor, sought legal advice, but because she was of sound mind, albeit brainwashed, she was deemed to have capacity and there was nothing we could do."
In Ghana, Mrs Fordham and Kofi were driving from Accra to the Oti region "to get approval from a family member for marriage" when their car left the road and crashed, fatally injuring Mrs Fordham, Mr Smith told the inquest.
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He said that there was no third-party involved in the smash.
Kofi later pleaded guilty to driving offences and was handed a suspended prison sentence and a fine.
Philip Spinney, senior coroner for Devon, Plymouth and Torbay, said at the end of the hearing: "I conclude that Janet Fordham died as a consequence of a head injury that was probably sustained in a road traffic collision."
Increasing numbers of women have been reported to be dying during pregnancy or in the weeks after giving birth.
According to the latest official data, there were 252 maternal deaths from 2022 to 2024 – 20% higher than the rates from 2009 to 2011. This is the equivalent of 12.8 deaths for every 100,000 women giving birth.
NHS England's chief midwife Kate Brintworth (CMO) told Sky News that, while improvements were being made, "none of us think care is in the right place".
"We don't think that things are good enough," she said.
Read more: Your birth trauma stories
"It's a terrible anguish to lose a child," she added. "I think it's one of the worst things that can happen to a human, and our responsibility as leaders in maternity is to make sure those families don't experience that anguish."
Ms Brintworth hopes today's announcements will ensure avoidable deaths are "significantly" reduced.
The Maternity Safety Alliance, a campaign group, said it was "alarmed" that Ms Brintworth's response to the data suggested "a lack of urgency, accountability and meaningful action" to the "long known and completely avoidable harm and death that is happening everyday in our maternity services".
"We yet again see the CMO avoiding giving proper answers to the critically important questions she has been asked, whilst also using language that screams of minimisation and denial," it added.
"What we have heard from the CMO today is completely detached from the reality women, babies, and their families face when using maternity services.
"Instead of the urgency we expect to see from the CMO, we are hearing a series of platitudes and false reassurances.
"What we need and expect from the CMO is clear leadership, accountability, and evidence of fundamental change in maternity services. As of today, CMO Kate Brintworth is providing none of these."
What's been announced?
The NHS says it will become the first healthcare system in the world to offer all pregnant women an early risk assessment for venous thromboembolism before their first antenatal appointment by next March.
The condition refers to blood clots that form in deep veins, which are now the leading cause of maternal deaths.
Anyone identified as being at high risk will be offered blood thinners to prevent clots within 72 hours.
Other changes to be brought in by March 2027 include giving every woman with epilepsy access to a local specialist team for managing the disorder in pregnancy, a tailored plan to help control seizures, and timely access to medications that are safe to use in pregnancy.
Women are also set to be routinely assessed for their mental health and referred to a specialist NHS perinatal mental health service if needed.
And those experiencing a haemorrhage or significant bleeding after birth will receive care from specialist obstetricians and anaesthetists sooner.
Got a question for Laura Bundock about this or any other story? Ask them here
It comes after Health Secretary Wes Streeting accused the NHS of having an "appalling culture of medical misogyny" as he set out a range of measures in a renewed Women's Health Strategy.
The NHS expects the full rollout of the measures in England will reduce the number of deaths caused by blood clots, strokes, cardiac disease, suicide, sepsis, obstetric haemorrhage and pre-eclampsia.
These account for 52% of maternal deaths.
It's also hoped it will tackle maternal suicides, which remained the leading cause of death occurring between six weeks and one year after the end of pregnancy between 2022 and 2024, accounting for 33% of deaths.
The NHS was contacted for comment about the Maternity Safety Alliance's criticisms.
More than 403,000 people are now diagnosed with a form of the disease every year, the report says. That is the equivalent of approximately one person every 80 seconds.
Cancer Research UK's report attributes the rise to an "ageing and growing population". Rates have risen by 15% since the early 1990s – partly due to factors like obesity.
Michelle Mitchell, the charity's chief executive, said: "More people are being diagnosed with cancer than ever before. Although cancer survival has doubled since the 1970s, progress has slowed over the last decade."
She added that the government's recently published National Cancer Plan "could make a big difference, but only if it turns into improvements for cancer patients".
Read more: Is new cancer strategy bold enough?
The Cancer in the UK Report 2026 describes the National Cancer Plan for England as a crucial step towards improving cancer care but says "there needed to be funding and resources to translate ambition into impact".
The charity warns urgent action is needed on early diagnosis and is concerned that just over half of patients in the UK are diagnosed at an early stage, noting this figure has barely changed in recent years.
It recommends rolling out lung screening widely to catch as many as 7,800 additional cancer cases per year – if the programmes in England were optimised.
Cancer Research UK also calls for improvements to cancer prevention, saying it is "essential" that the Tobacco and Vapes Bill – becoming law soon – be "effectively implemented". It will ban anyone born after 2008 from smoking.
The charity also suggests investing in specialist staff and equipment to tackle waiting times – with around 107,000 patients waiting more than 62 days to start treatment in 2025.
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A Department of Health and Social Care spokesperson said: "We have delivered a record number of diagnostic tests in the last 12 months, backed by an extra £26 billion for the NHS – and the number of patients getting a cancer diagnosis or all-clear on time is the highest in five years – but we are not complacent.
"Our National Cancer Plan sets out how patients will receive a diagnosis faster, treatment sooner and better support to live well with cancer, with the aim of 75% of patients diagnosed from 2035 to be cancer-free or living well after five years.
"Our historic Tobacco and Vapes Bill, which is due to come into law soon, will also protect future generations from cancer."




