The wide-reaching probe is set to “learn lessons” from the six-year-old’s death and will reportedly involve cooperation with the police, schools, social services and probation watchdogs. Arthur’s stepmother, Emma Tustin, 32, was jailed for 29 years for murder and child cruelty on Friday, while his father, Thomas Hughes, 29, was sentenced to 21 years for manslaughter.
Little Arthur died in June last year after Ms Tustin caused a fatal head injury in her Solihull home.
It was also discovered Arthur had been poisoned with salt, withheld food and drink and made to stand alone for more than 14 hours a day.
While out campaigning for the Tory candidate to replace Owen Paterson on Friday, Mr Johnson vowed to leave “absolutely no stone unturned”.
He said: “I just want to say, on the tragic and appalling case of Arthur Labinjo-Hughes, like many people I find it hard to read it, let alone to understand how people could behave like that to a defenceless little child.
“I’m glad that justice had been done, in the sense that they have both received tough sentences, but that is absolutely no consolation, and what we’ve got to make sure now is we learn the lessons about that case, we look at exactly what happened, what else could have been done to protect that child.
“It is early days, but I can tell you this, we will leave absolutely no stone unturned to find out exactly what went wrong in that appalling case.”
According to reports, teachers and family raised the alarm several times but police failed to act on the warnings.
Solihull’s Local Child Safeguarding Partnership has also launched an independent review after it was discovered social care workers had previously visited Arther two months before his death but found “no safeguarding concerns”.
A Government source told The Times every possible organisation that could have prevented the “appalling” tragedy will be held to account.
They said: “There can be no complacency after this appalling case, which is why we are widening the scope of this investigation by pulling in every possible organisation that might have been able to stop this and holding them to account.”