The General Teaching Council for Scotland (GTCS) decided that Derek Curran would remain on the register in January following allegations over his past conduct.
The 61-year-old was appointed as headteacher of Castlebrae Community High School, Edinburgh, in 2013 but he was suspended and later sacked the following year.
He had been accused of a string of failures dating back to 2014 when a young woman accused a teacher at the school of sending her around 40 sexually explicit emails.
An investigation was launched during which Mr Curran was also named by the woman.
She alleged he had a sexual relationship with her when she was just 15, and had his child after turning 18.
He faced allegations that he failed to “adequately assess the seriousness” or “properly conduct and progress” an investigation into the complaint against a science teacher.
It was reported that the student was paid compensation by the council in January 2016 over the emails from the teacher.
However, the GTCS faced backlash last month when they released their decision over the investigation – allowing Mr Curran to remain on the register.
A whistleblower that worked with the woman who received emails from the teacher issued a complaint to GTCS bosses over the ruling.
Today they published details of how they came to their decision after finding a number of the allegations not proven.
The panel found allegations that Mr Curran did not properly investigate the student’s claims about her teacher as “not proved”.
They said: “The panel considered the email trail within (CEC) City of Edinburgh Council following the receipt of Witness 2’s [a community programmes manager at Castlebrae Community High School] complaint.
“The panel noted that due to an apparent internal mix-up, the final version of the response email to Witness 2 had not been sent.
“The panel also noted that the terms of the email confirmed that the CEC’s Education Department – Children and Families was satisfied with the progress and conduct of the investigation undertaken by Witness 1 and the teacher.
“On that basis, the panel considered there was sufficient evidence that the actions taken by the teacher had been deemed appropriate by senior officers within CEC.
“Further to this, the panel carefully considered Staff: Allegations of Abuse policy and Child Protection policy, specifically regarding the historical child abuse, and was of the view that there was no persuasive evidence of significant deviation from this.
“In the panel’s view, the teacher’s explanation for the delay in telling Teacher A of the allegation seemed reasonable to the panel.”
Mr Curran admitted whilst in a ward at the Royal Hospital for Sick Children he behaved in a threatening or abusive manner, which caused a person to suffer fear.
In relation to the incident, the GTCS panel said: “The teacher’s representative submitted that with the panel’s knowledge of the teacher’s private life, there was an explanation of a stressful family situation, although this information was not a justification for the teacher’s behaviour.
“He submitted it was a temporary lapse on the part of the teacher which in the context provided was forgivable and which did not impair the Teacher’s current fitness to teach.”
He was found by the panel to have failed to adhere to Edinburgh City Council’s procedures in relation to a payment of travel expenses of £399.
“The teacher’s representative invited the panel to consider the evidence of the GTC Scotland witnesses who confirmed that there was a near unanimous view held by headteachers that savings could be achieved by accessing cheaper travel outwith the CEC’s procurement procedure.
“He invited the panel to note witnesses’ evidence that it was common knowledge within CEC that this practice was continuing and that efforts had been ongoing to address this long-standing difficulty in achieving compliance by headteachers.
“He submitted that a headteacher seeking to save public money could not amount to misconduct.”
In regards to the shortcomings of the teacher being remediable, the GTCS state: “The panel’s view of the teacher’s conduct in relation to behaving in a threatening or abusive manner, which caused a person to suffer fear whilst in a ward in the Royal Hospital for Sick Children was that it had been serious but that it was not fundamentally incompatible with being a registered teacher.
“[This is] due to the specific context of the behaviour which, albeit disruptive, had not resulted in physical harm and was rooted in a particular familial background.
“The panel accepted as genuine the teacher’s explanation of the background circumstances to the incident.
“The panel also noted that the teacher accepted full responsibility for his behaviour.
“The panel considered that the teacher had evidenced insight and remorse and it was satisfied that he appreciated the seriousness of the allegation.
“The panel considered that the shortfall in his conduct was remediable.
“The panel was persuaded that the shortfall identified had been remedied.”
The GTCS added: “The panel noted that there had been no further incidents in the intervening eight years.
“The panel noted that the matter had been brought before GTC Scotland and adjudicated upon and that the teacher had admitted the allegation in full and provided insight and remorse for his actions.
“The panel determined that the public interest did not require a finding of impairment against the teacher.
“Accordingly, for the reasons set out above, the panel determined that the teacher’s conduct does not currently fall short of the standards expected of a registered teacher and that his fitness to teach is not currently impaired.
“As the panel had determined that the teacher’s fitness to teach is not currently impaired, there was no need to proceed with the remaining stages of the hearing and this determination marked the end of proceedings.”
Following their decision to allow Mr Curran to remain on the teaching register last month, opposition councillors led calls for a more ‘robust’ review.
It was reported at the time that parents were ‘shocked’ at the decision to clear Mr Curran to return to the classroom.