Four children were sexually assaulted by their father over several years after agencies failed to adequately recognise symptoms of sexual abuse.

The Norfolk Safeguarding Children Board (NSCB) published a review of the case on Wednesday following the completion of criminal proceedings in January.

The father was jailed for life after pleading guilty to a number of rape and sexual assault offences involving a child under the age of 13.

An older sibling received a two-year suspended sentence after pleading guilty to sexual activity with a child family member.

The review said police and children's services failed to 'properly' investigate initial allegations of sexual assault.

And despite a high degree of agency intervention, the report said it took 'considerably too long' for decisive safeguarding action to be initiated.

It said allegations of sexual abuse against the father had been made as early as 2006.

In one incident, a five-year-old, identified as sibling one, was said to have been made to drink washing up liquid and perform sexual acts.

The response by children's services and police to this allegation was found to be 'wholly inadequate'.

It said the father was made to temporarily leave the house by children's services in order to resolve his mental health problems.

But he later returned home with no further assessment.

The report said no police investigation was conducted with the father and no crime was recorded.

'Children's services records suggest that attention was only on the washing up liquid issue and on the father's depression and mental health,' the report said.

'Both the absence of any serious follow up of the allegations of a sexual nature and also that the father simply returned to the home without any further assessment would have been considered very poor practice at that time, as it would be today.'

All four children lived with their mother in the family home.

The report said a large number of agencies were involved with the family over several years due to concerns about the children's welfare.

Those concerns included poor school attendance, home conditions and problematic behaviours.

All of the children were identified by the parents as having a range of underlying issues, such as ADHD or learning needs.

In 2014 there were discussions about potential foster placements for the two older children due to a worsening family situation.

However, it was not until the summer of 2015 that the eldest sibling was put into care.

The second oldest sibling was also put into care in October 2015. It was there that she made the sexual abuse disclosure which led to the father's conviction.

As well as the father being sentenced to life imprisonment, with a minimum tariff of 16 years, the mother was jailed for two years after pleading guilty to child maltreatment.

What the case review found

The serious case review said: 'Despite the commitment and best intentions of many of the professionals involved, the reality is that the multi-agency safeguarding system proved ineffective and too slow in its response.

'The reality that repeated sexual abuse within the family was taking place as well as neglect was only understood at the point sibling two was removed from the home and felt safe enough to tell her foster carer what had happened to her.

'It is unrealistic to conclude that sexual abuse in this family could have been completely prevented.

'However, the extent of that abuse and its continuation over such a long period of time could without doubt have been minimised.'

The case review found the different agencies involved with the family did not 'adequately recognise symptoms' which could have indicated sexual abuse within the family.

It said: 'Whilst there was a high degree of agency intervention it took considerably too long for decisive action to safeguard the children to be initiated.'

The review said a lack of adequate understanding and assessment of the adults in the family, their individual histories and their capacity or willingness to make the changes that were needed, contributed to the situation.

It also found a priority within children's services on reducing the numbers of looked after children made it difficult to move them into child protection or care.

The review made a series of recommendations including that NSCB and its partners continue developing its multi-agency approach to child sexual abuse to ensure it is not reliant on disclosure by victims.

Norfolk Police response

Chief superintendent Nick Davison, head of safeguarding and investigations, said: 'In Case U, which shows a long history of multi-agency involvement with the family, it is clear that the police investigation that took place back in 2006 was inadequate.

'Sadly this reflects upon a time in policing where the dedicated child abuse investigation team was under resourced and both national and local policing priorities were focused on other areas of our responsibilities.

'Since then, and within our current plans, the force has significantly invested in child abuse investigations and safeguarding with increased numbers of officers focusing on child abuse, stronger processes, greater training and improved leadership and oversight.

Looking to the future with the development of our new 2020 Investigations Hubs, we continue to make increased investment in our ability to tackle these complex crimes ensuring we are the strongest position possible to protect other vulnerable children and adults.'