Around 20 caravans moved onto the field at The Weald School yesterday (Thursday) and a notice has now been served on them to leave.
A West Sussex County Council spokesperson said: “There are currently 20 caravans parked on a field at The Weald school in Billingshurst.
"Notice has been served requiring them to vacate the land. Should they fail to do so, court proceedings will commence.
"We will continue to monitor the site together with Sussex Police.”