Grace Idowu, mother of murdered Tabard Gardens teenager David Idowu, has appealed to young people to turn away from knife crime.
The academy was formerly Geoffrey Chaucer School where her son's 16-year-old murderer was a pupil. David Idowu, aged 14, attended nearby Walworth Academy.
Grace Idowu began her address by describing the moment the police broke the news of her son's stabbing to her whilst she was at Tesco.
"How many more after David have lost their lives?" she asked the audience. "We don't want crime any more in Southwark.
"A knife is not a solution. Drugs are not a solution."
Appealing to young people in the room she said: "Listen to adults please. You cannot know more than adults. We are here to help you. We are here to raise you. Listen to us and let us be part of your life. You cannot do it yourself."
She also expressed regret that there were not more parents present at the meeting to discuss the danger of carrying knives.
Simon Hughes MP, taking Northern Ireland as an example, spoke of the great influence women can have for peace.
Turning to young males he said: "Realise that every time you take a risk by taking a weapon you add to the risk."
He also suggested that young people need to make teachers aware of anyone known to be violent or out of control and therefore a potential danger.
Globe Academy principal Jason Baigent, welcoming the guests, said: "There's a lot to be proud of in Southwark. There is a lot we can do together."
Other speakers included Southwark's head of community safety Jonathan Toy, Schools police officer Sargent Dave Snow, and former Globe student Amed Hussain representing Make Knife Crime History.