Hall later became the assistant director of Manchester Social Services, with hundreds of young children under his care.
A jury at Manchester Crown Court found the 67-year-old guilty of 18 counts of sexual assaults on children on Monday.
Ian Gray – Hall’s deputy between 1972 and 1976 – was also convicted in March of similar sexual offences against children in Manchester and in the West Midlands and was sentenced to 14 years in jail.
An earlier reporting restriction on Gray means that only now can we publish details of his crimes.
The evil duo’s depraved attacks were uncovered in a joint police and social services operation codenamed Cleopatra, which was launched in 1997 after a number of victims came forward.
They found that Hall – who before his conviction had moved to live in Northumberland – molested children in his car, at a number of houses he owned, during holidays and in a Manchester theatre.
Four of Gray’s victims were abused as a warden at a South Manchester children’s home, others were attacked at a centre in the West Midlands.
As the operation unravelled the extent of Hall and Gray’s crimes, 20 police officers and six social services investigators were assigned to the case, which looked at 60 care homes in Greater Manchester and two in the West Midlands.