The two social workers at the centre of the John Smith case both broke down in tears when they gave evidence at the trial.
A colleague of Dave Pamely and John Barrow, now both suspended, said: "They are good men but they are facing the sack. They have been destroyed by this."
A third professional, former health visitor Denissa Phillips, believes she was "sacked" over the case, a claim flatly denied by her employers, Worthing Priority Care Trust.
Mr Barrow, who has been a social worker for more than 15 years, and Mr Pamely were duped by the McWilliams into believing John was self harming.
They saw horrendous injuries on the four-year-old boy on numerous visits and, according to the inquiry report, could have taken action to rescue him.
Mr Pamely, described by colleagues as conscientious and meticulous, saw John as much more than just a "case" and showed genuine affection for the boy.
While John was in the care of his birth parents, Mr Pamely was praised for his diligence in monitoring the boy's welfare and looking into concerns.
But when John was suffering injuries at the McWilliams' home, Mr Pamely, according to the inquiry author Alyson Leslie, said: "...his ability to weigh conflicting messages and to analyse and respond sharply to situations was impaired by the workload pressures he had been experiencing."
By December 20, 1999, four days before John's death, he had been putting in the equivalent of five-and-a-half-weeks work in a four-week period.
Ms Leslie said Mr Pamely had told his manager he did not feel he could take on any more cases without his already heavy workload suffering.
No respite was offered and new work continued to be given to him.
He had had almost 20 years' experience and his supervisor relied on this and did not challenge his judgements as rigorously as she now believed she should have, the report said.
Health visitor Mrs Phillips declined to comment but a friend said her life had been wrecked by the John Smith case.
She worked for Worthing Priority Care Trust care for 13 years and saw bruises on the boy when she visited the McWilliams' home.
She told friends she was "sacked" a year after John's death, which the trust denies. It said she was working as a freelancer and therefore could not be sacked. If she had been employed, she would now be suspended pending an inquiry into her role in the case, according to trust spokesman Adrian Wardle.
Mrs Phillips blamed the trauma she suffered from the case for her split from her partner and the spoiling of an otherwise distinguished career.
Mrs Phillips, 69, was said to be considering legal action against the trust.
The friend said: "Her sacking came in the form of a letter from the trust a year after the boy died. She was employed just seven-and-a-half hours a week during the time she was visiting John and had many other children to check on.
"She informed managers there were potential problems with the McWilliams and there was not enough time to do the job properly but nothing was done."
Mr Wardle said Mrs Phillips worked as a part-time freelancer after her retirement at the age of 65. He said she never indicated to line managers that she did not have enough time to do her job properly or that there were problems with John.
He said the inquiry report highlighted a number of occasions when Mrs Phillips and others should have sought medical help for John.
He said: "Had she been a substantive employee, she would have been suspended pending an inquiry."
During her testimony, Mrs Phillips said the McWilliams told her about John's alleged self harming as early as August, four months before his death.
She said she told her line manager and child protection manager.
Mrs Phillips saw bruises and a so-called carpet burn on the boy's face during a visit on August 26.
There were no more visits by any health worker until November 22, a month before the boy's death. Michelle McWilliam told Mrs Phillips John had been selfharming and she saw facial bruising on him.
Mrs Phillips last visited on December 21, three days before his death. Again, he was self harming, according to the McWilliams.
Mrs Phillips told the court: "Because of the bruising, I wanted to see how John related to both parents."
A child would often shrink back from a parent who had abused them. John related well to Michelle McWilliam and did not shy away from either parent: "He was not frightened of Simon."
She said she left the house reassured there were no child protection issues.
Mr Pamely declined to comment.
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