Police and council officials last night used emergency powers to order travellers off a public park.
They posted notices on 15 caravans which had arrived at Surrenden Field, off London Road, Brighton, telling them to move by early today.
The caravans and assorted vehicles had damaged the turf.
The encampment was visible to delegates and visitors driving into Brighton for the Labour Party conference.
But Brighton and Hove Council says the fact the Prime Minister and Cabinet were in Brighton was not the reason for the quick action.
A spokesman said: "We asked the police to take action because Surrenden Field is a public amenity and the vehicles were damaging it."
Landowners and councils can only use the emergency powers available if there is evidence travellers are causing damage or posing a threat to an area.
It is up to the local police whether they agree that enforcement orders should be enforced.
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