The "self-centred" mother of Baby P was today jailed indefinitely for betraying him to die at the hands of her sadistic and abusive boyfriend.
An Old Bailey judge said she had covered up her little boy's horrific eight-month ordeal in order to save her relationship.
The 32-year-old boyfriend, described by the judge as a threat to young children, was jailed for life with a minimum of 10 years for raping a two-year-old girl.
He was also given a 12-year term to run concurrently for his "major role" in Peter's death.
Judge Stephen Kramer said he was "appalled" by the case and rejected the mother's lies that she was too naive to realise what was going on.
He described her as "manipulative" and "calculating" while giving short shrift to her last minute pleas for clemency.
The 27-year-old was told she must spend at least five years in jail and lodger Jason Owen, 37, of Bromley, Kent, a minimum of three years.
Judge Kramer made clear that even when these terms were completed none of the three would ever be released while they still posed a danger to children.
But child protection campaigners complained they could be free in "a few short years" when Peter should have been enjoying life as a schoolboy.
Haringey Council, whose social services department was supposed to have kept Peter safe, issued an unreserved apology for its failings.
The little boy was 17 months old when he was found dead in a blood-spattered cot in August 2007 having suffered a broken back and fractured ribs.
He had more than 50 injuries despite being on the at-risk register and receiving 60 visits from social workers, doctors and police over eight months.
Owen and the boyfriend were convicted of causing or allowing the death of a child at a trial in November, while the mother earlier pleaded guilty to the charge.
The judge said: "Any decent person who heard the catalogue of medical conditions and non-accidental injuries suffered by Peter cannot fail to have been appalled.
"It was clear that significant force had been used on Peter on a number of occasions.
"A child died in horrific circumstances with injuries that can only have caused great pain and distress prior to his death."
The judge said claims by each defendant that they knew nothing of the "climate of abuse and neglect" at the north London home where Peter died "defied belief".
He told the mother: "You are a manipulative and self-centred person, with a calculating side as well as a temper.
"I reject the suggestion that you were blind to what was happening in that house or that you were naive.
"Your conduct over the months prevented Peter from being seen by social services. You actively deceived the authorities.
"Health professionals who saw Peter shortly before he died seem at the least to have missed the import of the injuries to him.
"That does not absolve you from your culpability. You acted selfishly because your priority was your relationship with (the stepfather)."
The mother showed no emotion until her boyfriend was sentenced to life. Her mouth fell open as she appeared to mouth "No".
Minutes later she returned to court with her barrister in a failed bid to make the judge reconsider the indefinite nature of the sentence.
Judge Kramer also gave little weight to a handwritten letter she wrote yesterday to apologise for letting down her "darling" son. She will be eligible for parole in August 2012.
The judge said he would not indulge in "judicial speculation" about who killed Peter - but said the boyfriend played a "major role" in the ordeal, while his sex attack on a little girl was "abhorrent".
He was put on the sex offenders' register and disqualified from working with children. He cannot be released until August 2017 at the earliest.
"You are a threat to young children," the judge said.
Turning to Owen, he said: "What happened to Peter in the time that you were there happened in an atmosphere that allowed a complete lack of care to be ingrained with a sickening and descending loss of personal responsibility.
"You were more concerned about your own situation and about the horror of what was happening to Peter being discovered than taking steps to protect him."
Owen will be eligible for parole in August 2011.
NSPCC chief executive Andrew Flanagan said: "We are disappointed that the minimum tariff was so low. It raises the question of how bad the abuse has to be before offenders get a longer minimum time in prison.
"Baby Peter suffered sustained abuse leaving him with horrendous injuries.
"Two of his abusers could walk free at a time when Peter should be a schoolboy with a new world in front of him. Despicable cruelty has denied him that opportunity."
Haringey Council leader Claire Kober said: "We failed these children and I apologise unreservedly for the shortcomings and mistakes in our child protection service in 2007 when these crimes were committed."Reuse content