Police said the majority of those involved had already left the scene before their arrival, but officers arrested other youths over offences including possessing an offensive weapon.
A 13-year-old boy, who cannot be identified due to his age, has now pleaded guilty to possessing a knife in public.
At Bromley Magistrates’ Court earlier this week he was sentenced to a youth offender panel for four months.
Youth offender panels are a community-based way to deal with young offenders, aiming to help them take responsibility for their actions and prevent future offending.
The funfair was forced to close after the disorder but reopened the following day with safety measures including knife wands and CCTV.
In a statement, organisers Capital Funfairs said: “We are a family fun fair, for families, run by families.
“To support a family-oriented environment, children under the age of 14 will not be allowed entrance without an accompanying adult. ID may need to be shown to verify age.”
