A teenager was stabbed in his chest and left seriously injured in Burgess Park on March 2.
Police confirmed they were called shortly after 11am to reports of a stabbing, and a nineteen-year-old was found by London Ambulance Service paramedics.
Detective constable Rebecca Whiteley said: “This attack happened in a busy park when people were around exercising and walking through this public space.
“We would urge anyone who has any information that could assist us in our investigation to get in touch.”
No arrests have been made and enquires continue to establish what happened.
The victim remains in a serious but stable condition. Anyone who witnessed the incident or has any information is asked to call police on 101, or Crimestoppers anonymously on 0800 555 111.