Ceuta and Melilla are not comparable to Gibraltar, since they have been parts of Spain since long before the creation of Morocco. To an extent, they are comparable to the Falkland Islands, which have been under British sovereignty since before the creation of Argentina.
But the real way to make the point would be to offer the people of Gibraltar, so keen to be British, the option of incorporation into the United Kingdom, sending parliamentarians to Westminster as the inhabitants of Ceuta and Melilla send parliamentarians to Madrid, and paying the taxes levied at Westminster as the inhabitants of Ceuta and Melilla pay the taxes levied at Madrid.
They might not like that second bit, so the other option on the ballot paper should be independence. All but two of the British Overseas Territories, Montserrat and Saint Helena, are economically capable of independence. Yes, even including the Falkland Islands.
The Bermudian and Cayman Islands dollars have already been pegged to the US dollar for more than 40 years, while the US dollar is the official currency of the Turks and Caicos Islands. George Osborne, with your plan for compulsory registration at Companies House, watch out.