The lynchpin of Scotland's largest paedophile ring was free to work at the Celtic East Boys' Club in the 1990s, despite having a conviction for molesting a young boy almost a decade earlier.

Neil Strachan, 41, who is facing a possible life sentence after yesterday being found guilty of molesting an 18-month-old toddler, was convicted at Linlithgow Sheriff Court in 1985 of abusing a boy but went on to work as secretary for the young footballers' club in Edinburgh in 1995.

This was because strict rules surrounding who can work with children were not in place at the time Strachan took up the position at the club.

It later emerged that he was found guilty of indecently assaulting a boy between the ages of five and 11, between June 1994 and June 1996.

He was jailed for three years for that offence in 1997 but the court heard that the offences were not connected to the club in any way. He was placed on the sex offenders register.

Disclosure Scotland was created in 2002 to enhance public safety by providing potential employers or organisations with criminal history information on individuals applying for paid or unpaid posts.

Employers are notified by Disclosure Scotland of all past convictions of anyone on the sex offenders register and advised not to allow them to work with children.

John Murphy, 31, who was also convicted yesterday of offences in relation to possession of indecent photographs of children, was allowed to continue working as a drama teacher at Claremont School in East Kilbride after being found guilty of taking part in a homosexual threesome in Glasgow city centre. He was struck off by the General Teaching Council but later won a legal battle at the Court of Session to be allowed to teach again after it ruled that irrelevant information had been put before the committee which had later informed its decision.

Disclosure Scotland is now a Scottish Government agency.

It had been called upon to check the background of Neil Campbell, 46, the church bellringer from Jordanhill, but he had no criminal convictions to alert the church to his sexual lustings for young boys.

The same was true of James Rennie, 38, who had in the past worked as a secondary teacher and latterly as the chief executive of LGBT Youth Scotland. Last night the organisation welcomed his conviction and said their thoughts were with the child victims and their families.

In a statement released by the board, it said: "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. That there is no suggestion that James Rennie directly threatened the safety of young people accessing our services is due to the culture of child protection within the organisation, which is backed up by robust policies."