"I confronted the teacher with my concerns and evidence and it was in the best interest that she left the school that morning."
The teacher subsequently resigned.
Mr Sturch said the boy's welfare was the school's paramount concern and since he was first made aware of the allegations the student had met with a counsellor and his parents were notified.
"The student is still seeing the counsellor and there will be follow-up work with the councillor and his family [in] term three."
"Our primary responsibility is with the boy concerned."
Mr Sturch did not believe the relationship had been going on for long and speculated a couple of months.
"I don't think it was a prolonged relationship, not a lot just stays private within a school environment."
Police had not been brought in to deal with the incident since the boy was over 16 years of age, which meant it was an ethical and professional issue rather than a legal one.
However, the case had since gone to the New Zealand Education Council Complaints Assessment Committee and a spokesman said the investigation was ongoing.
"The Education Council received a mandatory report from Hastings Boys' High School on Monday 26 June and on Wednesday 28 June we obtained an 'undertaking not to teach' from the person in question."
The spokesman said the 'undertaking not to teach' was about protecting student safety and to remove the teacher from the environment where the allegations had been made.
Mr Sturch said the teacher's formal closure of employment with the school meant it could move forward in the new term, however, it would still be following up with the student and his family to ensure his welfare.
