The right-wing stance on Gibraltar is that it is 'embarrassing' for Spain for a foreign power to have foreign enclaves within Spanish soil. To take this argument further, one could consider Portugal to be a similar 'enclave'.
The more considered opinion is that Gibraltar's position as a tax-free haven for businesses is depriving Spain of money. Gibraltar has approximately five times as many registered businesses as there are people living in Gibraltar.
Spain also accuses Gibraltar of being a hotbed of drug smuggling, tax evasion and money laundering.
Gibraltar points out that Article 1 of the UN Charter contains "principle of equal rights and self-determination of peoples". They also remind the Spanish that the Treaty of Utrecht, despite being nearly 300 years old, is legally binding and guarantees Gibraltar's position as a colony of the United Kingdom.
Many also argue that there is no place in today's world for petty arguments about sovereignty. Calling Gibraltar's presence at the negotiating table 'humiliating' (see above) weakens Spain's claim, as it appears to be more about pride than practical considerations and the rights of the people involved.
Gibraltar's position as a colony means that it is not technically a part of Spain and so does not infringe on the rights of the Spanish people. It is certainly not 'occupied' territory, in the same way that Portugal, which also shares the Iberian Peninsula with Spain, cannot be considered occupied.
Spain has been accused of hypocrisy considering that it has seven territories in Morocco and Moroccan waters: Ceuta, Melilla and the islands of Isla Perejil, Isla de Alborán, Islas Chafarinas, Peñón de Alhucemas and Peñón de Vélez de la Gomera.
Great Britain's Stance
The opinion of the citizens of mainland Britain is largely one of apathy: the Gibraltar Question does not arise in UK politics. The British Government's stance is considered to be that Gibraltar is a messy situation that causes friction between Spain and the UK and that an outcome that is satisfactory for all three sides is desirable.
Some progress has been made recently, Gibraltar's presence at the negotiating table in recent discussions amounting to an acceptance of its existence by the Spanish government.
Some deals have been struck in recent months, including an agreement to allow flights from Gibraltar airport to other destinations in Europe (at present only flights to the UK are permitted) and increased rights for Spanish pensioners living in Gibraltar.
