Andorra is a tiny principality located between France and Spain, and although the jurisdiction was a bone of contention between the two countries during the Middle Ages, it has had de facto independence since 1278, when France and Spain decided to be 'co-princes' of the region. In 1993, Andorra declared a new constitution, becoming an independent European state with a democratically elected parliament..

However, the 'co-princes' still theoretically retain responsibility for the principality's foreign affairs and defense matters, and Andorra has traditionally enjoyed a close relationship with Spain and France.

Gibraltar news service, Panorama, has suggested that the Foreign Office has withdrawn the file - dated in 1971, soon after the total frontier closure imposed by the Franco regime, and titled 'Possible Andorran Solution to the Problem of Gibraltar' - because of its political sensitivity during the ongoing negotiations between the UK and Spain.

The newspaper suggests that the Foreign Office may fear that the file will upset the Spanish Government, who are keen to leave open a path to sole sovereignty over the Rock, despite the British insistence on joint sovereignty.