The murder of eight-year-old Victoria Climbie, in 2000, exposed fatal weaknesses in the nation's child protection procedures.
Antoine and Kenniece Ogunkoya were killed at their mother's flat
Three years later, Lord Laming's inquiry into the killing focused in detail on how the different child protection agencies had failed Victoria.
Five years on more relatives are grieving over the failure of what the peer called "basic good practice" which has led to the deaths of more vulnerable children.
Children like Antoine and Kenniece Ogunkoya, who were killed by their mother Vivian Gamor in January 2007.
Antoine, 10, was beaten around the head with a hammer and then strangled while Kenniece, three, was suffocated with cling film and her corpse stuffed into a black bin bag.
Their mother had shown frequent signs of mental illness for three years claiming the children had been swapped at birth.
Eventually she was sectioned as her condition deteriorated and was diagnosed with schizophrenia.
Twenty-eight days later she was discharged as doctors believed her condition could be controlled with drugs.
The children's father Jimi Ogunkoya, who was raising the children with his parents, became concerned when social services suggested that the children stay unsupervised overnight with for Vivian.
The assessment had been made after she was given a supervised visit.
"I had reservations," said Mr Ogunkoya.
"I could not understand how someone could be in hospital for a month and be fine to look after children," he added.
"Don't get me wrong, I didn't think she was going to kill them but I thought she was unwell and I was concerned that the children were staying with an unwell person.
But there was a crucial piece of information Jimi and his family only found out when Vivian Gamor was sentenced last August at the Old Bailey.
They learned for the first time that Ms Gamor had been sectioned for attacking her half sister with a knife.
"If I had known then, what I know now I would not have agreed to unsupervised overnight visits."
The children were killed on the third unsupervised visit to their mother.
Mr Ogunkoya said he is finding it hard coming to terms with their loss.
"I should be on the school run or taking Antoine to football."
His ex partner is now being held in a secure psychiatric hospital after admitting manslaughter due to diminished responsibility.
Judge Peter Rook QC told her: "On the face of it this terrible tragedy could have been avoided if you (Gamor) had not been allowed unsupervised access and the children's father's grave concerns had been given weight."
Fran Pearson, chair of Hackney and City Safeguarding Children's Board, a multi-agency body which oversees child protection, said she could not comment fully on the case until the results of an inquiry were heard.
She told BBC Radio 4's File On 4: "Where there are issues to be addressed they will be addressed."
This was the kind of case Lord Laming hoped his report, released five years ago, would avoid.
The peer told the BBC he despairs that in some parts of the country the flaws he highlighted in child protection are being repeated.
After studying this case he said: "It seems to me that had the whole range of services been directed to supporting that mother and thinking and bringing to bear all their different resources it may have been possible to prevent that mother doing what I don't imagine she ever intended to do and the children paid the ultimate price for the failure of organisations to actually carry out their duty."
Hear the full story on Radio 4: File on 4 Tue 22 Jan 2008 GMT, repeated Sun 27 Jan 1700 GMT or online at File on 4 website