When Arthur died, he had more than 130 areas of bruising on his body, was malnourished and had salt levels in the system that medics described as “off the scale”.

But when social workers examined him just weeks before his death, they reported that there were no concerns and concluded any bruising was the result of “play fighting” with Tustin’s other children.

Arthur Labinjo-Hughes’ death a ‘terrible tragedy’

A Solihull Council spokesman said: “This terrible tragedy has had a shocking impact on Arthur’s family and across the whole community. We send our heartfelt condolences to everyone affected.

“The circumstances around his death will now be subject to an independent review – the Local Child Safeguarding Practice Review – and clearly it would be inappropriate for the council to comment ahead of the findings of that review.”

West Midlands Police, who visited Arthur eight weeks before he died, reported that he appeared “safe and well”, despite receiving photographs from his uncle showing his numerous injuries.

The police watchdog said it had carried out an investigation into the force’s handling of the case and would report in due course.

Joanne Hughes, Arthur’s grandmother, told the trial how she felt there was “no one else to go to” after repeatedly raising her concerns with the authorities.

His uncle, Daniel, was even threatened with arrest over lockdown rules if he went back to the youngster’s house to check up on him.

The NSPCC said the pair’s convictions “must be just the start of the process to uncover the full chain of events that ultimately led to Arthur’s death and to establish the lessons that need to be learned to prevent this awful case from happening again”.

Boy pleaded: ‘Please help me’

Jurors sat through eight weeks of harrowing evidence that charted the cruelty Hughes and Tustin meted out to the little boy in the final months of his life.

This included denying him food and water, making him sleep on the living room floor and forcing him to stand for hours in isolation.

He was ritually insulted and subjected to foul-mouthed diatribes by the very people who were supposed to be caring for him.

Tustin used her mobile phone to record hundreds of clips of the little boy being abused, mocked and physically attacked.

In one heartbreaking audio message, Arthur could be heard pleading for his uncle Blake, to whom he was denied access.

He could be heard saying: “Please help me, help me uncle Blake, they’re not feeding me. I need some food and drink.”

Hughes removed his son’s favourite teddy bear and cut up his prized Birmingham City football shirts in front of him.

On another occasion, he duped the child into thinking he was going to see his beloved grandparents – before turning around.

In the weeks before his death, they stepped up their campaign of cruelty and began poisoning him with salt.

A medical expert who assessed sodium results in the little boy’s blood on his admission to hospital found 34mg – a level so high it was off the “normal scale”.

Arthur was so emaciated when he eventually collapsed that medics attempting to revive him noted that they could see his ribs through his skin.