Gibraltar was seized by the British in 1704 and the Spanish ceded sovereignty in 1713 under the Treaty of Utrecht. But Spain has retained a constitutional claim over the territory situated at the gateway to the Mediterranean.
The narrow peninsula was cut off from Spain in 1969 by Gen Francisco Franco when he closed the border from Spain. It was not fully reopened again until 1985, almost ten years after Spain's transition to democracy.
Since 2006, with the creation of the Tripartite Forum for Dialogue, the governments of Spain, Britain and Gibraltar have sought to build a framework of co-operation to improve the life of those who live and work in Gibraltar and the Spanish towns across the border.
However, the mayor of La Linea, the Spanish town bordering Gibraltar, has threatened to introduce a tax on those crossing in an attempt to cash in on the large number of visitors to the Rock. Mayor Alejandra Sanchez of the right-wing Popular Party claims that the socialist government in Madrid has sacrificed the town of La Linea's interests, favouring Gibraltar, to ensure good relations with Britain. He argues that "millions of visitors cross the town to get into the British colony each year", and that most of Gibraltar's income comes from visitors from Spain. "Meanwhile, we have 10,000 unemployed in La Linea. This truly intolerable situation cannot continue," he said.
The town hall of La Linea is said to be close to bankruptcy with recent demonstrations from council workers protesting that they had not been paid their wages.The mayor has therefore ordered a study on the legality of charging vehicles and pedestrians using the border crossing a nominal fee to help swell town council finances.
Critics of the mayor point out that 7,000 Spanish workers are registered as officially employed in the tiny territory and countless others provide services or supplies. Added to which, many of the 28,000 Gibraltarians own homes over the border in Spain because of a shortage of affordable housing on the Rock itself.
Mayor Sanchez has already been summoned to Madrid by Spain's foreign minister to explain recent hostile action to those attempting to cross into Spain from Gibraltar. Last week he was reprimanded for ordering the local police force to halt vehicles crossing into Spain and carry out document checks, an act that caused long delays and was labelled as "harassment" by Gibraltar's government.