Inadequate management allowed a "predatory" male nurse to manipulate 23 women patients into sexual relationships, an inquiry has found.
David Britten, 54, a former manager at the Peter Dally Clinic in Pimlico, central London, preyed on patients over a 20-year period.
Claims by patients of sexual misconduct emerged after his dismissal from the clinic in 2002 over unrelated issues.
The NHS launched an inquiry in 2006 into how he escaped detection.
The inquiry was originally commissioned by North West London Strategic Health Authority, which is now NHS London.
The investigators blamed poor management, missed opportunities and the reluctance of his victims to come forward as the reasons for Mr Britten "grooming vulnerable patients".
The report described Mr Britten as a "manipulative predator who represented a clear danger to women".
Alison McKenna, who led the inquiry, said: "The effect of David Britten's abuse of these vulnerable women cannot be overestimated.
"David Britten was a specialist in eating disorders and would have known that affected individuals can be very compliant and eager to please.
"He deliberately targeted vulnerable patients, grooming them for his own sexual gratification".
Mr Britten, who is believed to be living in northern France following the allegations, has not faced any criminal charges as the Crown Prosecution Service said there was insufficient evidence.
Sarah Harman, the lawyer for some of the victims, said their lives have been "ruined by the way he behaved".
The woman, named only as Victoria, said she was in a sexual relationship with Britten for more than a decade and claimed other members of staff at the clinic were complicit in his affairs.
Calling for four other members of staff to face disciplinary action, she said: "What I really want is for this man to be tracked down and shamed. He has got away with this and he is laughing at us.
"But I also think the other professionals who were well aware of his affairs have gotten off too lightly.
"They knew exactly what was going on - I remember one member of staff waving us away as I went home with him in his car."
Apologising on behalf of NHS London, chief nurse Trish Morris-Thompson said: "As a nurse and a midwife, I am appalled by David Britten's actions and that they went unchecked for so long.
"He abused not just these women but also his position of professional trust".
The report said although the NHS took appropriate steps and dismissed Mr Britten, the Nursing and Midwifery Council (NMC) was criticised for failing to suspend or strike him off the nursing register until 2004, despite the claims against him since 2002.
The report also raised questions over four other former members of staff, two of whom still work within the NHS.
Professor Morris-Thompson said the NMC was "very unhelpful" during the inquiry and confirmed many notes collected in the 1980s had gone missing.
NHS London said they were seeking legal advice following the report's publication.
In 2001, Peter Dally Clinic closed after it was taken over by the Central and North West London Mental Health Trust and sexual allegations against Mr Britten emerged.
A new eating disorder service was opened a year later with new staff.