The case of little Preston Davey, abused to the point of death by his adoptive parents, Jamie Varley, 37, and his partner, John McGowan-Fazakerley, 32, is utterly chilling.

Poor little thing never stood a chance. His biological mother, Sarah Davey, is a convicted killer who brutally murdered a pensioner when she was aged just 14. Preston was born four weeks premature and taken into care five days later.

He had a brief period of respite with his foster parents Sandra and Paul Cooper before being matched, aged nine months, with his killers. What should have been a new start for a happy, healthy little chap turned out to be the beginning of the most brutal of endings.

As a mother, I can hardly bear to read the details of what they did to him. But the video shown to the jury of him being jolted awake by Varley on the eve of his first birthday gives us an inkling. It shows a degree of coldness towards a small child that I find simply incomprehensible.

It reminds me of that awful footage of poor Arthur Labinjo-Hughes, aged six, captured on CCTV installed by his mother, too weak to walk or support his own weight, toppling over as he struggles to carry his bedding, crying that ‘no one loves me’ and ‘no one’s going to feed me’.

In the footage of Preston, the toddler is filmed falling asleep despite the cacophony from the TV and bright lights, clearly exhausted. He is sitting upright, unclothed, his head wobbling. Any normal person would have tucked him up in bed with his teddy.

Instead, Varley continues to film him then suddenly shouts ‘Boo!’ and he is startled awake. The look that crosses his little face is so sad, a mixture of fear, confusion – and a heartbreaking lopsided smile, perhaps a desperate attempt to invoke some degree of mercy from his tormentor.

Not for the first time, one finds oneself contemplating the merits of the death penalty.

As well as the Labinjo-Hughes case, this also reminds me of another, similarly incomprehensible case of child abuse that shocked the nation a quarter of a century ago: Victoria Climbie.

Climbie was an eight-year-old girl from the Ivory Coast whose parents sent her to live with her aunt, Marie-Thérèse Kouao, and Kouao’s boyfriend, Carl Manning, in 1999. They hoped for a better life for their child than the one they could provide back home.

But it was not to be. Almost immediately, Victoria was subjected to the most horrific catalogue of abuse, including being stripped naked, bound in a plastic bag and locked in a freezing bathroom.

She was forced to eat her food off the floor and beaten with a bicycle chain, a hammer and coat hangers. In February 2000, she died from organ failure due to severe malnutrition, weighing just a little over three stone and with 128 wounds on her body.

Preston’s injuries were similarly horrific, including some attributable to the most repulsive and frankly unimaginable catalogue of sexual assaults.

He was 13 months old when he died of suffocation due to an object being forced into his mouth. The autopsy revealed deep tissue bruising to his mouth, bowel, bladder and bottom, as well as lacerations to his rectum.

What kind of person does those things to an innocent little baby? Apparently a perfectly respectable middle-class couple with an immaculate lifestyle and no previous convictions.

But appearances can be deceiving, and monsters can be very cunning.

In the Climbie case, Victoria’s primary carer Kouao, was a highly manipulative, calculating individual who played the system audaciously to her own advantage.

For example, on one occasion she actually took Victoria to Tottenham Social Services (where they lived) claiming that her lover, Manning, had been sexually abusing her in order to deflect growing suspicions about Victoria’s mistreatment from herself.

Likewise, with Preston’s case, Varley was the primary carer, having decided to take a year off work to look after him – and he also seems to have been a highly cunning, skilful manipulator.

His performance in the dock after the sentence was read out – dry retching and collapsing – was mirrored in footage of him becoming hysterical at the hospital.

Cradling Preston’s dead body he wailed: ‘I’m going to hell.’ As McGowan-Fazakerley tried to console him, he hung his head and said: ‘I probably won’t see you again.’ Even in that moment, all he could think about was himself.

But there is more here than simply the behaviour of highly malicious individuals. In the Climbie case, it was concluded at the subsequent inquiry that many of the ‘red flags’ that might have alerted social services and medics to the child’s plight were ignored or dismissed on ‘cultural’ grounds.

In other words, people were reluctant to accuse Kouao of wrongdoing on account of her ethnicity. And it wasn’t just Kouao’s own behaviour that was excused on this basis; white colleagues were scared to challenge the views of the black social workers involved, namely Lisa Arthurworrey and her managers.

This extended to accepting Kouao’s explanation for severe scalding on Victoria’s body that she had a rare African skin condition, and ascribing Victoria’s meek behaviour in the presence of her carers to a ‘cultural trait’.

Ultimately, the inquiry counsel Neil Garnham QC concluded that ‘fear of being accused of racism can stop people acting when otherwise they would’.

Lord Laming’s subsequent public inquiry in 2003 was supposed to usher in a new era of safeguarding, including better communication between services and a whole raft of other measures. But the truth is, as Preston’s case tragically shows, nothing has really changed.

In particular, the political correctness and confirmation bias that helped seal Victoria’s fate remains. In Preston’s case, worries about doubting the ability of this same-sex couple to parent a toddler appear to have been set aside or dismissed, and Varley’s half-baked excuses were given the benefit of the doubt when clearly they should have been interpreted as serious warnings.

His birth grandmother, Debbie Davey, has said that in her view the judgment of social workers was clouded by ‘political correctness’.

‘Social services might have been hesitant to take action when they saw Preston because they may have been accused of being homophobic,’ she said, adding: ‘They didn’t see through them and see what was going on to Preston. As soon as you see a baby with a broken arm, you ask questions.’

It must be said that Mrs Davey was opposed in principle to the child being placed with a gay couple, having stated that children should be raised by ‘a mum and a dad’.

But her concerns were rejected, and she was told that Varley and McGowan-Fazakerley were ‘the most beautiful people’ who would give her grandson everything.

This case should not provoke a backlash against same-sex adoption. Bad people come in all shapes, sizes, colours and sexual orientations, and there are plenty of children being raised in same-sex relationships who have wonderful parents.

Equally, there are many heterosexual couples – like Kouao and her partner and Emma Tustin, little Arthur’s mother – who should be nowhere near children.

But this wilful reluctance to see the bad in someone purely because they come from a certain group lies at the root of so much that is wrong in our society.

It was the reason that the police seemed uninterested in investigating the hundreds of working-class white girls being raped and tortured by Pakistani men across two decades in several counties; it's the reason poor Henry Nowak wasn't believed when he said he had been stabbed and died being read his rights, while the real criminal stood by smirking.

It’s the reason Valdo Calocane was free to murder three people (the decision not to section him was based on concerns of ‘over-representation of black males in detention’).

It’s arguably the reason those three traveller boys were let off with non-custodial sentences after raping two girls (those sentences are now thankfully under review).

This institutionalised political correctness – in the police, the judiciary, social services and beyond – is utterly toxic, and this poor dead baby is just the latest victim. A quarter century on from Climbie, isn’t it time we finally learned that lesson?