Grattan Puxon, from Dale Farm Housing Association, expressed disappointment at the decision.
Gypsies and travellers living on one of the UK's largest unauthorised sites, near Wickford in Essex, have lost their latest battle against eviction.
The group was initially given a temporary reprieve by the High court after Basildon Council ordered them to leave the site at Dale Farm.
In January, the decision was overturned after an appeal by the council.
Three senior law lords have now dismissed an appeal by the travellers to challenge the ruling.
Lord Justice Pill who was sitting with Lords Justices Lloyd and Moses said that in his view the council had acted "lawfully" in the stance it had taken.
Half of the 1,000 people living at the farm do not have planning permission.
A spokesman for Basildon District Council said they "continue to work with other organisations to assist travellers who are relocating from these sites.
"Fundamentally, these cases are about the need to uphold planning law for the benefit of the whole community while taking full account of the needs of individuals who require a place to live in accordance with their cultural heritage.
"The council expects to have further discussion with the travellers on how best to achieve an orderly withdrawal from these sites."
Last week, the travellers were supported by a committee from the United Nations.
The UN group on forced evictions is recommending the district council grant planning permission where needed or offer alternative land for the travelling community.
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