An Auckland schoolteacher coaxed and groomed a primary school student into a close relationship before committing sex offences against him, a jury was told today.

Nicholas Raymond Baldwin, 62, is on trial in the High Court in Auckland facing two charges of sexual violation, eight of doing indecent acts with a young person and one of meeting a young person following sexual grooming.

The name of the boy, and that of the school he attended and which Baldwin taught at, is suppressed.

Crown prosecutor Josh Shaw said Baldwin was noticed by colleagues at the school getting very close to the boy, often meeting outside the classroom.

Mr Shaw said colleagues noted the "special relationship" but perhaps brushed aside its significance as Baldwin was experienced and well-regarded, though one told him he should not be alone with students.

But two women Mr Shaw described as "netball mums" became concerned in August 2008 and followed Baldwin and the complainant to an Auckland rugby clubrooms, where they took photographs of them behind the clubroom which showed very close contact.

They took videos of the pair at a reserve the next day, after which police were contacted.

Police then took over surveillance and one officer noticed "three periods of prolonged kissing", after which they intervened.

The complainant was interviewed by police describing how the relationship began as non-sexual in 2006 before it graduated to cuddling, light kissing and then heavier kissing and sexual touching.

He said they often went to hiding places, like behind rugby clubrooms, "because we didn't want anyone else to think we were gay, because we weren't".

Mr Shaw said the interview showed "how much of a hold the accused had over the complainant, how well coaxed and groomed and manipulated he was. He didn't regard it as particularly wrong."

A few days later an envelope was found at the accused's house containing notes expressing the complainant's love for Baldwin and a pair of the boy's boxer shorts.

At a second interview he talked about how he would act out some "wet dreams" of Baldwin's.

Baldwin's lawyer Roger Chambers said there was no doubt a close relationship developed but that nothing untoward happened.

"He denies totally any sexual grooming whatsoever. He totally denies any sexual misconduct at all."

Video evidence from the boy, in which he describes how Baldwin was touching him sexually, was played to jurors this morning. The boy said he had not told anybody because Baldwin told him not to.

The trial before Justice Geoffrey Venning is expected to last a week and a half.