Neglect was recognised by social workers but was "never really addressed" before a baby boy was killed from a catastrophic brain injury, a serious case review has found.

Katherine Cox, 33, and her boyfriend Danny Shepherd, 26, were jailed in November last year after being convicted of causing or allowing the death of five-month-old Eli Cox, in an attack that left him with injuries compared to those of a car crash victim.

As well as the head injury, baby Eli was found to have 28 fractures, within 19 different bones, and had also been exposed to drugs at his home in Lapwing Close in Minster, Sheppey.

Scroll down for video

The cause of his death, in April 2016, was a result of a serious head injury caused by shaking.

The couple were also convicted of possession of a class B drug (amphetamine). They were sentenced to eight years and 13-and-a-half years imprisonment, respectively.

A serious case review, published today, found a series of failings. There was evidence of workers being "overly optimistic" about improvements in how the baby, referred to as Child D, and his siblings were being cared for.

A summary of the report by Kent Safeguarding Children Board (KSCB) said: "There was a catalogue of domestic abuse and drug and alcohol use by the adults in this family.

"The impact of this on the children was not assessed.

"Neglect was recognised, and despite being considered for legal proceedings, was never really addressed.

"Also, whilst the parents appeared to co-operate, with hindsight, it is less clear that they actually were."

It added: "On occasions, there were signs of improvement in how the children were cared for, however, these improvements were never sustained despite continued support from professionals working with the family.

"There was evidence of workers being overly optimistic with the observed improvements and the parents were rarely challenged when the improvements were not sustained."

The serious case review also found that "minimal information" was known about Cox's partner Shepherd by professionals working with the family and a detailed assessment of him as a new family member was not undertaken.

Concluding the report, Gill Rigg, the independent chair of KSCB, said: "This is a tragic case, and the KSCB has thoroughly, independently and openly reviewed the circumstances of Child D’s short life and death.

"This is to ensure that all lessons are learned so that improvements are made to multi-agency working in future safeguarding cases.

"As a result of their contributions to the serious case review, the relevant partners have drawn up individual recommendations and action plans for improving the way they continue to work to protect children in the future.

“The report also has recommended a number of multi-agency actions to be overseen by the KSCB to make sure that action is taken, as needed.

"This is crucial as part of helping improve the safety and wellbeing of Kent children. These have already been implemented and lessons learned.

“The KSCB’s role and function has always been, and remains, totally committed to continually improving the protection of vulnerable children and young people in Kent.”

There are 10 recommendations in the report, which have been accepted and actioned by the Local Safeguarding Children Board (LSCB).

A spokesman for Kent County Council said: “The death of any child is an appalling tragedy, and our deepest sympathies are with those extended family members who suffered the loss of a son, brother, cousin and grandson.

“The report concludes that no professional had seen signs of, or had reason to suspect, the violence perpetrated against Child D which resulted in his death.

"However, in reviewing this case alongside partner agencies, it became clear there were important lessons for everyone to learn when working together to support complex families with multiple risks and challenges such as this.

“The SCR review process has identified a number of areas in our own practice we can improve, and we have worked very hard to provide better support and challenge to families such as these.”

An NSPCC spokesperson said: “The circumstances surrounding the death of baby Eli demonstrate the impact a neglectful home environment and chaotic parenting can have on young children.

“The report makes clear there were signs Eli and his siblings were at risk of abuse.

"It is vital that lessons are learned and the recommendations in the serious case review are implemented to minimise the risk of this happening again.

“We all have a duty to look out for the welfare of children.

"If anyone has any concerns about a child please call the NSPCC’s helpline, free and in confidence on 0808 800 5000.”