5th August 1908
The British Ambassador in Madrid informed the Spanish Minister of State ‘as an act of courtesy’, of the British Government’s intention to build a fence along the line of British sentries on the isthmus to prevent smuggling and reduce sentry duty.
According to the British government, the fence was erected 1 metre inside British territory. Spain currently does not recognize the fence as the valid border, since it claims the fence was built on Spanish soil. Even though Spain, the United Kingdom and Gibraltar are all part of the European Union, the border fence is still relevant today since Gibraltar is outside the customs union. The border crossing is open 24-hours a day as required by EU law.
Image source: Gibraltar Panorama Paper May 20, 2015