Then I actually read the story about it and saw that it was Spain that left the soil to the British in 1713...
https://en.wikipedia.org/wiki/Status_of_Gibraltar
After reading about it, I don't think the UK gonna give it back just because Spain asked it nicely. It has been three hundred years
Same with Falkland islands but that never stopped the UK, even going to war for them in the 80ies. History says the Argentinians had some prison there which was "liberated" by some Privateer (This Falkland guy) and the Argentinians never took it back until the 80ies. It is way too far from the UK, incredibly expensive to keep running, little or no strategic value, production is sheep, maybe some fishing but not much else. Only recently there is new controversy of possible oil in the ocean surrounding it.
The UK used to be a world naval Empire with colonies all over the world, they released most of them, but not all.
Like Gibraltar, if Falkland were truly returned it would probably end neglected in poverty. Independence with benefits, like most UK ex-colonies could be a way. But they might not be able to sustain themselves on their own.
BTW: The British made the Falkland fox go extinct for daring eat some sheep here or there, not unlike the Portuguese did to the Dodo. Of course nobody cared about preservation a couple hundred years ago...