Among the crimes was a shocking sexual attack carried out on a three-month-old baby boy by an executive adviser on child sex issues.
James Rennie, chief executive of a publicly-funded gay rights group, was one of the men exposed yesterday as members of Scotland's biggest paedophile ring.
Rennie, 38, molested the toddler son of unsuspecting friends - a little boy he had been trusted to babysit - recording the abuse and sharing it with other perverts.
In the course of the police investigation, the boy's parents were forced to watch a video of their baby son being violated by Rennie.
Last night, after the eight men were found guilty of a string of child sex charges at the High Court in Edinburgh, the child's parents reacted with disgust.
They said: 'For over 15 years, James Rennie seemed the closest of family friends and it is hard to put into words the extent of the betrayal he has exacted upon us.'
During their investigations, police recovered tens of thousands of still and moving images of the most vile child abuse. 
Police sources revealed yesterday that the activities of 70 other men around the UK with links to the case are being investigated.
More than 35 people have been arrested or been subject to enforcement action. Two investigations are continuing in Scotland.
One of the most worrying aspects of the case is the way Rennie was able to reach a position where he could influence Executive policy on child sexuality.
A trained teacher, Rennie became the boss of LGBT Youth Scotland, a publicly-funded support group for lesbian, gay, bisexual and transgender young people.
He took on the £40,000 a year role when the group was set up in 2003 and became the Executive's most important and influential adviser on gay issues affecting children.
Under his leadership, the group backed proposals to allow gay adoption. As well as appearing in the Scottish parliament, he was invited to a Royal Garden Party and to Downing Street.
Yesterday, Rennie, from Edinburgh, was found guilty of indecently abusing the baby boy. The abuse began when the child was three months old and continued for several years. Rennie filmed and photographed himself committing the abuse, sent the images to others and allowed another man to listen on the phone while he molested the child.
He allowed the boy, whom he called his 'nephew', to be abused by another paedophile and also offered him to other deviants in a series of emails.
When his home was raided in December 2007, Rennie had gone to the trouble of hiding computer hard drives, discs and CDs in a gap next to the water tank in his kitchen. Between these storage devices and his laptop computer, he was found to be in possession of thousands of images, many of them at the most extreme level of the scale.
Rennie carried out his vile activities as part of a Scottish paedophile ring swapping images of child pornography on the internet.
He was suspended as soon as LGBT Youth Scotland was told of his arrest in December 2007 and resigned soon afterwards.
Last night, a spokesman for LGBT Youth Scotland, which received £1.1million in 2008 from the Executive, councils and health boards, said: 'We are appalled by the abuse and exploitation of children by James Rennie, and wholeheartedly welcome his conviction. Our immediate thoughts are with the children and families who have been directly, and indirectly, abused by him and the other co-accused also convicted.
'We had no suspicion whatsoever of the crimes James Rennie was committing. He was obviously skilled at hiding his actions and adept at deceiving people. There is no suggestion James Rennie directly threatened the safety of young people accessing our services.'
Last night the Executive said that it would continue to fund LGBT.
When he was arrested, Rennie had a steady boyfriend, but trawled the internet looking for gay sex dates.
He also used the internet to meet other paedophiles, including Neil Strachan, a child molester who was jailed for three years at Edinburgh Sheriff Court in 1997 for abusing a boy of between five and seven.
Strachan, 41, joined Rennie for a sex session with Rennie's 'nephew' at his flat in Meadowbank when the boy was between one and three.
Rennie then boasted about the encounter to another paedophile, Lachlan Anderson, 51, from Cumbernauld, Dunbartonshire. Anderson is currently serving a 20-month sentence after being caught with a collection of child pornography, including images of Rennie abusing the child. He was brought from jail to give evidence at the trial.
Strachan was found guilty of attempting to sodomise a different 18-month-old toddler on the night of Hogmanay 2005 at his flat in the Dalry area of Edinburgh.
Last night, the boy's mother said: ' The anguish I feel towards Mr Strachan is indescribable.
'I feel that no matter what punishment is given to Mr Strachan it will never be able to compensate for the hurt, devastation and great deal of stress brought to me and my family.
'Mr Strachan used and abused our trust in order to satisfy his and others' sick needs.'
Strachan's 23-year-old boyfriend Colin Slaven was cleared of taking part in the sex act, which was photographed and sent to Rennie.
Rennie involved John Milligan, 40, in his sick acts by allowing him to listen to the baby boy being abused.
Milligan also discussed getting his hands on the child - and passed on images of Rennie's abuse to others.
The paedophile ring was uncovered when photos of naked boys were found on Strachan's computer. He handed it in for repair at a company in England in 2007.
A computer engineer found one indecent image of a child on the machine and police were called in.
An examination by Northumbria Police revealed other images.
The inquiry moved to Edinburgh, where Operation Algebra was set up in October 2007 by Lothian and Borders Police.
Detective Superintendent Allan Jones, senior investigating officer in Operation Algebra, said of the men: 'Many of them wouldn't stand out from a general member of the public; but in the background they lead this double life, looking at some of the most vile material you would ever care to imagine.
'Quite what motivates them and why they take this course of action I really don't know. What I do know is we can't be forgiving of it and we've got to pursue it to the nth degree to make sure that this material is stopped.'
A jury found Rennie, Strachan, Milligan, Ross Webber, 27, and Craig Boath, 24, guilty of plotting to arrange access to children to carry out acts of gross sexual abuse. It is the first time a conspiracy charge has been used successfully in Scotland to convict perverts.
Church bell ringer Neil Campbell, 46, was cleared of that charge. But all six, along with Slaven and John Murphy, 44, were found guilty of charges relating to child pornography.
Having been convicted of actual physical abuse of children, Rennie and Strachan face a possible life sentence.
Prosecutor Dorothy Bain, QC, asked for 'a full risk assessment' which would allow the court to impose an order for lifelong restriction - under which a judge imposes a minimum sentence but the accused are only freed when the parole board considers it safe to do so.
They then remain under strict supervision for the rest of their lives.
Judge Lord Bannatyne said: 'I am going to go down that route and investigate an order for lifelong restriction for both these accused.'
All eight men were remanded in custody to await sentence.
