The deaths of the six Philpott children in a house fire started by their parents "could not have been predicted or prevented", a serious case review has found.
The report carried out by the Derby Safeguarding Children Board in the aftermath of the tragedy found that while various professionals who had contact with the family could not have foreseen the fire, there were chances to get to know the family better.
A statement from the board said: "The board concludes that the tragic deaths of the children could not have been predicted or prevented.
"However, given the notoriety of the father, the incidents of domestic abuse and visibility of the children, there were some opportunities to get to know the family better although this would not have led to professionals becoming aware that there were plans to deliberately set fire to the house when the children were sleeping."
Mick and Mairead Philpott were jailed in April last year, along with their friend Paul Mosley, after being found guilty of the manslaughter of Jade Philpott and her brothers John, Jack, Jesse, Jayden and Duwayne.
The children's parents and Mosley had hatched a plan to frame Philpott's former mistress who had recently left the family.
The serious case review found that the living arrangements at Victory Road were "unorthodox and not one that professionals often come across" because prior to the fire, Mick Philpott had lived at home with his wife and his former mistress, along with their 11 children.
At the time of the blaze he lived in the council house with just his wife and the six children who died in the fire.
The serious case review said that agency checks not long before the fire would have revealed "happy, well-adjusted children" but available information would have confirmed Mick Philpott as "manipulative and controlling" but there was little known at the time about violence in the household, and no grounds for statutory intervention.
The report stated that the set-up at Victory Road was "not kept secret" and known to a number of agencies, as well as being well-known through Mick Philpott's appearances on television and in newspapers as he appealed for a bigger council house.
Records reviewed included several references to the unusual adult relationships, the report said, "but none indicate any concerns".
Various professionals who visited the house commented positively on the family atmosphere and how Mick Philpott engaged with his children, and saw no problems between the two women.
The serious case review said of Mick Philpott: "While he was known to be challenging to some professionals and in the media, there does not appear to have been any reflection or professional curiosity as to what he might be like at home and the impact of this on his family.
"There is also no information on the father's history or any exploration of his experience of childhood.
"Several agencies did not know of his violent past; had they, they may have considered their assessment of him differently at the time of their involvement."
Philpott was convicted in 1978 for attempted murder and wounding with intent on a former girlfriend and her mother. Following his release from prison because he did not have any children, nor was his offence against any, there would have been no requirement for the local authority to be alerted.
In 2006 there was an assessment by agencies concerning domestic violence against Mairead Philpott but this was "explained away as insignificant by the family" and treated as minor.
But the report added: "However, if health staff had been aware at the time of the father's earlier conviction, it is likely that this incident would have been cause for greater concern and investigation."
It went on: "Children's Social Care practice at this point here could and should have been more thorough, with checks being made on all the children's files, the police being contacted again for any information and further contact made with the health visitor to ask whether she had seen the two mothers.
"It would however have been difficult to review all the siblings' files as records were kept on paper and would have had to have been manually retrieved.
"It is not known why this did not happen but there were pressures to maintain the throughput of work and, as information had been obtained verbally before, it may have been considered that the social worker should move on to other more urgent cases."
The report also added that it would have been "best practice" for the social worker to have seen both mothers alone, but given the information available at the time it is likely any assessment would have been one of "low risk".
Overcrowding at the Victory Road property was considered by the report, especially after Mick Philpott had made numerous appeals in the media to get a bigger house from the local authority.
The review stated that there was no evidence at any time that there were health and safety issues relating to the number of children in the household and no concerns had ever been reported about fire safety in the home, which was fitted with working smoke alarms at the time of the fire.
The serious case review made a number of recommendations to various agencies, some of which it said have already been implemented, including ensuring multi-agency risk assessment conferences consider not just the victim, but all children who possibly remain at risk from the perpetrators.
Derby City Council said in a statement: "When six children die in such tragic circumstances there is an expectation that the local safeguarding children board will review the work of the agencies involved, even if, as in this case, the children were not considered to be children in need.
"Recommendations associated with council services relate to practice improvements, there being no causal link determined by this extensive and detailed review, between current practice and the tragic events that occurred."