Looks like the parent went to the News Shopper, which is the local paper in SE London. Telegraph et al have lifted the story from there.
This is the statement from the school from their FB page:
You may have seen a news item recently that refers to an incident in an English lesson at Tallis. What follows is an official response from Carolyn Roberts, Headteacher at Thomas Tallis School:
“A parent contacted us with concerns about a written exercise given to a class during studies of a play by Shakespeare. The exercise was given to a class who had been studying Macbeth as part of a year 8 English lesson.
“ The exercise was to write a suicide letter from Lady Macbeth to Macbeth explaining her decision to kill herself. The exercise is a well-known method for getting students to understand this dramatic twist in the play. The teacher who set the exercise is very experienced. Indeed, the exercise has been praised at our most recent Ofsted inspection for the progress made by pupils studying the play*.
“We appreciate that the exercise was upsetting to the family and have discussed the subject matter and approach with teaching staff. I met with the parent last week and apologised wholeheartedly on behalf of the school and reassured them about the actions that have been taken. The parent accepted the apology in a meeting that was friendly and cordial.
“We care deeply about the emotional wellbeing of our students and of course wish no distress to be caused to any of our students - all we can do is hold discussions and debates on topics such as these in a supportive and sensitive way. Had we been aware of any students who would have found the exercise upsetting then we would of course have taken a different approach. We have listened to the concerns raised by this debate and will not run the exercise again.
“I apologise again, for any distress that this may have caused to the family.”
We are happy for parents/carers with any concerns to contact Vanessa Cummins, PA to Carolyn Roberts, Headteacher at Thomas Tallis School, who will arrange an opportunity for a full discussion.
*Quote from the Ofsted report:
"In a Year 8 English lesson, students made very rapid progress when they were sharing their ideas about Lady Macbeth's feelings."