Peace activists camping in Parliament Square Gardens have lost their battle against eviction in the Court of Appeal.
The demonstrators, who are protesting against issues including the war in Afghanistan, had set up a tented camp they called the "Democracy Village".
Last month a High Court judge granted eviction orders sought by London's Mayor, Boris Johnson. That ruling has now been upheld.
Jan Luba QC, for the protesters, argued that Mr Johnson had no right to evict the demonstrators because he did not own the land, which belongs to the Queen.
But making the ruling yesterday, Lord Neuberger said that while the Crown owned the title to the land, the Mayor had the power to act over the square.
Colin Barrow, leader of Westminster City Council, said: "We all support peaceful protest, but it is completely unacceptable for parts of our city to be occupied and turned into no-go areas by vociferous minorities."