Tree-top protesters yesterday vowed to appeal against a High Court ruling that they must leave the tree houses they have built some 30ft above the ground.

The court said the squatters posed a risk of "serious harm to persons and property".

The protesters, known as the Protect Our Woodland group, are fighting plans to cut down 210 trees in Titnore Woods, Durrington, near Worthing, to make way for 875 proposed new homes and a new Tesco.

After yesterday's ruling, one of the protesters said they would use "whatever legal means are available" to win their fight and said they were prepared to maintain their tree-top vigil throughout winter.

Another, who gave his name as Dave, said: "With so much land being built on we are going to be left with virtually no green space for future generations."

The Protect Our Woodland group put up notices eight weeks ago claiming squatters' rights in Titnore Wood, a designated site of importance for nature conservation with oak, ash, birch and willow trees. The landowners claim the area the squatters are on is known as Lake Rue and is not actually part of the wood.

The protesters have since established an "Ewok village" of 15-20 tree houses linked by aerial walkways.

Yesterday, the High Court granted landowner Clem Somerset, possession of the land on the basis that the protesters were unlawful occupants.

Mr Somerset and his father, Fitzroy, argued in court that the protesters had created "a substantial risk of public disturbance and harm to property".

Three environmental activists - Jim Mutley, 25, Charlie Wells, 28, and Shaun Lewis, 40, an arborist and professional tree surgeon - argued unsuccessfully that they were engaged in a peaceful protest and the claim should be struck out.

Yesterday, protesters at the site said they would resist attempts to move them on.

Hollis, 22, said they had been buoyed by strong support from the community. He said people had donated food, clothes and money to ensure they could continue.

Another of the campaigners, called Hazel, said: "Worthing Borough Council and the landowner have ignored the vast level of opposition to this development, which has seen something like 1,000 letters of protest written."

Fitzroy Somerset said: "I understand that the defendants are going to appeal so I can say nothing until that appeal has been heard."