Gibraltar was captured in 1704 by a force led by Admiral Sir George Rooke representing the Grand Alliance on behalf of the Archduke Charles, pretender to the Spanish Throne.

In that treaty, Spain ceded to Great Britain "the full and entire propriety of the town and castle of Gibraltar, together with the port, fortifications, and forts thereunto belonging ... for ever, without any exception or impediment whatsoever."

Spain stating they believed the forum no longer existed and that only ad hoc discussions on local issues should take place with Campo de Gibraltar also included.

The latter resolution states that: any colonial situation which partially or completely destroys the national unity and territorial integrity of a country is incompatible with the purposes and principles of the Charter of the United Nations and especially with paragraph 6 of Resolution 1514 (XV) of the General Assembly [...] Invites the Governments of Spain and the United Kingdom of Great Britain and Northern Ireland to resume without delay the negotiations provided for in General Assembly Resolutions 2070 (XX) and 2231 (XXI), with a view to putting an end to the colonial situation in Gibraltar and to safeguarding the interests of the population.From such a point of view, Gibraltarians are seen as mere "settlers" from the United Kingdom and other countries and only their interests, not their wishes (as the right to self-determination would involve), need be safeguarded.

The first formal proposal on how to achieve the return of Gibraltar to Spain was made on 18 May 1966 by the Spanish Minister of Foreign Affairs, Fernando Castiella.

As a result, the UN General Assembly, during its twenty-third session, adopted resolution 2429 of 1968 (XXIII), denounced the 1967 referendum and requested the United Kingdom not to delay negotiations.

In view of that, the Spanish position seems to have softened, being redirected towards some form of temporary or permanent arrangement to achieve joint sovereignty, which has been proposed by Spain and discussed with the British Government.

The details of the proposal were not made public, but information released showed an offer on a treaty with the United Kingdom in order to "re-integrate" Gibraltar with Spain, while preserving Gibraltarians' way of life.

In 1997 a second proposal was made by the Spanish Minister for Foreign Affairs, Abel Matutes, foreseeing a hundred-year period of joint sovereignty before a definite transfer to Spain.

[31] A similar scheme was provisionally agreed between the Spanish and British governments in the spring of 2002, but this was eventually abandoned, after sustained opposition by the Gibraltarians that included the Gibraltar sovereignty referendum of 2002.

[35] From 2010 Spain has claimed that the trilateral dialogue is finished and reverted to the original call for a bilateral agreement with the UK with four way ad hoc meetings which would include Campo de Gibraltar.

In a letter to the UN the British representative, Emyr Jones Parry, writes: "The new constitution provides for a modern relationship between Gibraltar and the United Kingdom.

[citation needed] The United Kingdom further claims title to the southern half of the isthmus based on continuous possession over a long period.

Questions about the waters have previously been asked in the House of Commons, and answered as follows: Under international law, States are entitled, but not required, to extend their territorial sea up to a maximum breadth of 12 nautical miles.

Where the coasts of two States are opposite or adjacent, the general rule is that neither is entitled, unless they agree otherwise, to extend its territorial sea beyond the median line.

[46] At the end of 2008, the European Commission included most of the territorial waters that surround Gibraltar under a marine conservation area known as the "Estrecho Oriental" that will be maintained by Spain.

[53] The Spanish government wanted to increase the exchange of fiscal information[52] in order to prevent Gibraltar banks being used for tax evasion and money laundering.

The British government wanted concrete evidence of wrongdoing to warrant an investigation as Gibraltar has always complied with all international and EU requirements to prevent such activity.

In 2014, inspectors from the EU's fraud office OLAF wrote to the Spanish governments urging an investigation of tobacco smuggling, amid revelations that Gibraltar, with a population of less than 30,000, imported 117 million packets of cigarettes in 2013.

[59] In 2015, Spanish authorities broke up a major tobacco smuggling operation, seizing 65,000 packs of cigarettes, five boats, two firearms, communications equipment and €100,000 cash.

The British admiral Lord Fisher stated that Gibraltar was one of the five keys that locked the world, together with Dover, Alexandria, Cape of Good Hope and Singapore, all of which have been controlled by Britain at one point.

[61] Its military relevance has reduced with the construction in 1953 of the US Naval Station Rota (the biggest Allied base in the area) and with the end of the Cold War, but it is still an important position as more than one quarter of the global maritime traffic transits through the strait every year.

British National Archives files from 1953 show that Franco claimed that Spain had been promised The Rock in return for staying neutral during the Second World War.

Said Spanish communiqué did exist; however, a confidential memo called it "a flimsy and unconvincing document", and the Government put an end to the dispute by refusing to comment on the claims.

[76][77][78] The Government of Gibraltar claimed in December 2007 that the operation did not represent a material risk to the environment since the vessel had been defuelled and only small, remnant amounts of fuel remained in the engines themselves.

[81] 2009 – The dispute over British-claimed territorial waters gained prominence with deliberate incursions by Spain, triggering angry headlines in the UK tabloid press.

The Spanish officers were released by the police the following day, who said that "Enquiries established that the Guardia Civil mistakenly entered Gibraltar Territorial Waters in hot pursuit and have since apologised for their actions.

Relations between Britain and Spain reportedly "returned to a state of growing confrontation" following the election of Spanish prime minister Mariano Rajoy of the People's Party in December 2011.

The British Foreign office responded to these comments: "The prime minister has made clear that the UK government will meet its constitutional commitments to the people of Gibraltar and will not compromise on sovereignty.

[92][93][94][95] However, on 19 November 2018, the Spanish Government threatened not to support the Brexit Agreement Draft because they say that an article was added without their consent that could be misunderstood and leave Spain without a say over Gibraltar.