Marsom signed an agreed statement of facts with NCTL in July 2017 "in which she accepted the conduct alleged occurred but denied it was sexually motivated," the Teachers Disciplinary Tribunal said in a decision released yesterday.
"Ms Marsom stated that the believed the situation was blown hugely out of proportion and taken out of context," the tribunal said.
"She stated there was no inappropriate contact with [the student] prior to January 2017. She denied her conduct was sexually motivated."
But the tribunal has ruled that Marsom committed "serious misconduct" and has cancelled her NZ teaching registration.
It said Marsom was employed as a physical education teacher in Britain from September 2015 to March 2017.
The 17-year-old student, described as "Student E", "was known by Ms Marsom to be vulnerable, having previously received treatment for depression, anorexia and anxiety".
Marsom was her netball coach.
"In November or December 2016 the director of sport at the school raised with Ms Marsom the amount of time that she and Student E were spending together at the school. No further concerns were noted by the school until the police matter arose," the tribunal said.
"On two occasions Student E visited Ms Marsom at her home. On at least one of these occasions they watched DVDs together. Ms Marsom denies that they were alone on these visits.
"On February 4 [2017] they exchanged text messages from 2am for a period of a few hours. These text messages included messages of a sexual nature.
"Student E sent a message to Ms Marsom stating words to the effect that she was feeling 'horny' or 'kinky'. Student E sent Ms Marsom a picture of a male and stated she would 'f--- his brains out'. Ms Marsom sent a message agreeing by laughing.
"Student E sent a message to Ms Marsom stating that she loved her. Ms Marsom responded with words to the effect of 'please tell me more' with several question marks.
"Ms Marsom sent a message to Student E stating that she also feels kinky. Student E responded with words to the effect that Ms Marsom had 'missed the chance to come over'. The messages contained references to Student E being a lesbian and Ms Marsom wanting Student E to tell her more.
"Ms Marsom sent a message to Student E to the effect that she 'feels all funny inside when she sees her'.
"Student E was reported as missing by her parents on February 4. Police located the above messages on Student E's phone."
Marsom told the Herald that the texts were taken out of context.
"What I told them over there is that a lot of the contact was taken out of context. It was a lot of just joking around, and on reflection it was obviously not the right thing to do," she said.
She said she had not taught again since returning to New Zealand, did not intend to return to teaching, and was now "finding employment in other areas".