Enfield council said the park gates were locked at 4.50pm on Friday. In a statement, they said:
"While the thoughts of the entire council are with the victim of this horrific crime and her family, it is worth bearing in mind that parks by their very nature are designed to be accessible and it is extremely difficult to prevent access to people determined to break into them.
"We take all crime extremely seriously and our parks police work closely with friends of parks groups and park users to deal with any concerns raised in relation to safety in our parks.
"We will be co-operating fully with the police in an effort to bring the perpetrator of this horrific crime to justice and would urge anyone with information to ring the police."