Indeed She is, as well as mentioning Spain's OWN history of Colonisation, and the striking similarity in the positions of Gibraltar , Ceuta and Melilla..
Sadly only HM Government can revoke the invitation..
Apples and oranges (as always when the Gibraltar – Ceuta&Melilla thing arises). I think we all can benefit of putting some facts into context, shall we? Because using Ceuta and Melilla as scapegoats is quite unfair and almost offensive for a Spanish like me.
Summary: NO, Ceuta and Melilla ARE NOT like Gibraltar.
Argumentation:
1- Legal status, or What is a colony (and What is not):
You said it before: Spain, just as Britain, has a colonizer past. But Spain, unlike Britain, DOES NOT HOLD any colony nowadays. Not only Ceuta and Melilla are not colonies today, they never were on the first place.
The United Nations Chart contains a Declaration Concerning Non-Self-Governing Territories, a list of places that the United Nations General Assembly deems to be "non-self-governing" and subject to the decolonization process. The list was first established in 1946. Some of the original territories have been removed and others have been added. Gibraltar has been on the list since 1946 and remains, even after the various referendums in which the locals manifested their wish to remain as a British colony. The current list can be found here (no hint of Ceuta/Melilla. We’ll explain that):
http://www.un.org/en/events/nonselfgoverning/nonselfgoverning.shtml
To be removed from that list has been a long ambition of the sucesive governments of Gibraltar. Actually, it’s quite difficult that, given their current legal and political status, they can cease to be considered a colony. Many countries mantain some overseas territories. For instance, and just choosing a different example from Spain or Britain, the overseas French territories: French Guiane, Guadeloupe, Martinique, etc. These are not considered colonies, but overseas national lands. Why is so? Overseas regions have exactly the same legal status as mainland France’s regions: they have representation in the French Parliament, their inhabitants are French citizens in equal status and rights, they vote in the Presidential Elections. And, maybe above all, all the French laws and regulations apply (mainly) in those territories in the same way than they do in the mainlands. They are, to all effects, as much as a French territory as Provence.
That is equally the status of Ceuta and Melilla to Spain. They are considered part of the autonomous communities of Spain, with an autonomy and dependence from the State equal to any other region of Spain (same as the autonomous community of Madrid, for instance), their citizens are Spanish, they can vote in the same conditions and to the same elections as every Spaniard, they have representation at the parlament (as all autonomies do) and the Spanish constitution and laws apply there in the same way as it does in the rest of the country.
Gibraltar is a whole different story to these cases. It is no part of the United Kingdom, although it’s administrated by it and, although individually their citizens hold all the rights of every British citizen, they have no representation at the parlament and (and this is the question where every concern lies) they have their own legal system, although mainly base don the English one, but with their own constitution and laws approved by their own parliament. Moreover, when the UK joined the EU, a significant part of the negotiations was to mantain Gibraltar out from many of the European common legislation, quite significantly the common customs territories and the common comercial policy and it is, if I remember it correctly, the only territory inside the EU with such an “special” legal status. That is what has lead Gibraltar to become a tax haven and a nest of smuggling.
I assure you, you’ll never find such an enormous and problematic legal hole in Ceuta and Melilla.
2- The “Historical” status (you can never claim what never belonged to you)
The history of “occupation” of Gibraltar and Ceuta and Melilla is so different that it is actually the cause for such a different legal status.
It’s Morocco who claims the soberanity in Ceuta and Melilla against Spain. But, while Ceuta has been a Spanish territory for 420 years and, before of that, a Portuguese one for 84, and Melilla has been Spanish for over 500 years, Morocco only exists as an independent State since 1956. Morocco was before that a French – Spanish Protectorate, but Ceuta and Melilla had been complete Spanish territories for a lot longer than that, and for that reason they could not be claimed by Morocco at the time of its Independence.
In Ceuta and Melilla’s case, the historical relation with the Iberian territories is such that, even in the Middle Ages and under the Muslim occupation of Spain, they were under the Cordoba’s Caliphate ruling. They were always either under the peninsular ruling or that of small independent kingdoms in the North of Africa.
If we base the claims for the cities in History, only Portugal could call for Ceuta, because any other State that occupied them before Spain does no longer exist.
Once again, completely different story to Gibraltar. Gibraltar was part of Spain's territories until 1704, when it was occupied by the English Crown, during the course of the Spanish Succession Wars (together with the island of Menorca, that was later given back to Spain –in the 19th century, I think). It was King Felipe V of Bourbon, the winner at the war, who granted the sovereignty over Gibraltar (and Menorca) to Britain, through the Utrecht Treatry in 1713. A treatry, by the way, that has been constantly transgressed by Gibraltar and the UK, blatantly occupating the established neutral area that conforms the border between the two countries (among other ways, by building there the city’s airport).
I don’t know if the qualification of the UN as non-self-governing territory, or the breaking of the original Treatry’s terms by the UK are enough reason for Spain to claim back the sovereignty of Gibraltar against the opinions of the locals showed on the polls. IMO it's not, and I could not care less.
But wouldn’t it be nice if, for just one time, the UK would not try to hide the “no international laws” status and the problematic that the “special snowflake” legislation of Gibraltar causes to Spain and to the EU under those childish claims that Spain “does the same” because that is simply FALSE.
I mean he and his parents have the order if Charles III which they can easily wear to the event. Am I wrong in thinking they may simply award orders to those members who don't currently have them like Camilla and the Cambridges?
Some nice recap from past UK - Spain State Visits, from @RoyalFamily 
