One child a week is being murdered in Britain, in cases which echo the horrific death of Baby Peter, because clear warning signs that they live with a potential killer are being ignored or go unreported by key public service workers from police officers to GPs, according to new figures.

An in-depth analysis of the records relating to the deaths of 163 children killed at the hands of a parent or carer in the last five years has shown that thousands of children from babies to 16 are "slipping through the net" of protection measures despite the knowledge that they live in households with a history of domestic abuse, drug problems or where there has been a recent separation – all factors which dramatically increase the risk of murder.

The study shows for the first time the dramatic rise in the number of child homicides over a five-year period, with the number of killings doubling from 28 in 2004 to 56 in 2007, the year when Baby Peter was killed by his mother, her boyfriend and their lodger. He sustained more than 50 injuries, including a broken back and ribs, which were not spotted despite 60 visits by social workers.

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Incomplete figures for 2008 suggest the upward trend is continuing, and children are being killed by their so-called carers at the rate of one a week.

But the findings, which will be broadcast next week in a Channel 4 Dispatches documentary entitled The Children Britain Betrayed, suggest that despite the massive publicity surrounding the death of Baby Peter and the gross failings of social workers in charge of his care at the London Borough of Haringey, the child protection system overall is remarkably effective.

Researchers found that while there are about 30,000 children in Britain who are the subject of child protection plans, about two of those children are killed by a parent or carer each year. Of the 163 killings in the last five years, only 11 children, or seven per cent, were under the care of social services departments, leaving 93 per cent who were not being monitored by the authorities.

Instead, the programme found that a series of risk factors and warning signs, including a history of domestic violence or mental illness, were present in most of the killings and had not been recognised by professionals such as health visitors and social workers as putting that child in danger.

No fewer than 75 children, nearly 50 per cent of the total, were killed by parents who had been violent to an adult partner in the past and whose record was known to police, health visitors or social workers. Only two of these children were also on the child protection register.

The study also highlighted the dramatic increase in risk to children when parents separated or announced they were separating. A total of 43 children were killed in those circumstances with four, including seven-year-old Amy Philcox and her brother Owen, three, who died when they were on unsupervised access visits ordered by the courts.

In another case, a toddler was stabbed to death by his father despite the fact that his mother had been a regular victim of domestic violence and was raped at knifepoint by the man. The child was not placed on the "at risk" register and neither police nor social workers warned the mother that her son could be at risk if his father was allowed unsupervised access.

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Another significant factor was the presence of a diagnosed mental illness among parents or carers who went on to kill a child. The study found that 30 per cent of cases – and 50 killings – involved an adult who was under medical supervision.

Lynn Ferguson, the investigative reporter who led the research, said: "It is simply a scandal that we have a situation where the vast majority of these children are being killed despite the presence of very clear warning signals, in particular with domestic violence. There are 300,000 children in this country who live with serious domestic violence in their home and they are being allowed to slip through the net, despite the fact that it has been recognised as a significant risk factor for many years.

"Our social work system is so over-stretched that risk assessments of children in these situations are simply not carried out. We don't need a full protection plan in all these cases but there is clearly a need for better monitoring."

The study finds that there is an onus on all individuals who come into contact with children – health visitors, police, GPs, probation officers, school teachers and members of the public – to recognise the warning signs associated with adults whose previous history makes them more likely to kill.

The introduction of a compulsory annual visit by a health visitor or trained advocate is suggested to ensure that the most at-risk children (about 68 per cent of cases involved children from birth to four) can express concerns to a professional.

Amy Howson, 6 months: Father broke daughter's spine in anger at her crying

Tina Hunt was ecstatic when she first met James Howson and moved in with him. But soon after their first child, Amy, was born, Tina became withdrawn and would not speak with friends in the street. A routine health check for Amy went unattended and efforts by health visitors to see the child were unsuccessful. It transpired that Howson was subjecting his daughter to a horrific catalogue of violence. A post-mortem found 40 injuries, including six fractures to her arms. Amy died on 23 December 2007 when Howson, angry at her crying, placed her across his knee and broke her spine. He was jailed last year for 22 years.

Ryan Hawkins, 4: Stabbed in revenge for affair

Val Hawkins' marriage to her husband, Chris, was defined by alcohol. The couple ran a pub near Huddersfield and when drunk Hawkins would become violent towards his wife but, despite being arrested three times, charges were never brought. After eventually leaving her husband, Val was persuaded to leave their youngest son, Ryan, with his father. After raping his wife, Hawkins was served with an injunction preventing him contact ing Val or Ryan. However, through the couple's two teenage daughters he persuaded Val to allow him contact with Ryan. When Val phoned social services to ask their advice, she was told they would call back. They did not. On 23 September 2007, Ryan's sister, Donna, arrived at Hawkins's home to collect the boy. Hawkins proceeded to stab her 23 times. She escaped but Ryan's body was later found with nine stab wounds. Hawkins, who was jailed for life, said he had killed the child in revenge for his wife having had an affair.

Amy Philcox, 7, and Owen Philcox, 3: Gassed in the car after divorce

When Lyn Philcox filed for divorce from Brian, her husband of eight years, in 2007, she noticed his behaviour become increasingly erratic as he sought to monopolise the attention of their two children. Once he jumped out from behind bushes and grabbed hold of their daughter, Amy, telling her: "I love you Amy, I love you, your mum can't stop me from seeing you."

After receiving a series of mobile phone pictures, including one of her patio doors wired shut, Mrs Philcox rang social services, but they said that they could do nothing. Despite evidence of Brian's stalking, a judge allowed him unsupervised access to his children two days a week and an overnight stay every other weekend.

During one of these overnight stays, in February 2007, on the day his divorce was made final, Mr Philcox took his children on a trip to North Wales.

After sedating Amy and their son, Owen, he called Lyn and told her: "There's nothing I can do. It's out of my control now." He then gassed the children and himself in his car.

Police later found an explosive device in his house that had been designed to kill Lyn.