If it belongs to the people who live there, why does Britain have any say in their matters?

Gibraltar have had two referendums on whether they want to be a part of Spain or the UK, and they have voted with an absolutely insane majority to choose to be part of the UK in both cases. This isn't like Brexit, or Scotland's IndyRef - there was a 96% turnout and a 99% vote in favour of the UK in 1967, and an 88% turnout with a 99% vote in favour again in 2002.

Why does Britain have any say in the people who live in, say, Liverpool? Because that's historically been British territory. So what's the difference? Only real difference I can see is length of history (a few hundred years vs. nearly a thousand years). But as far as I'm concerned, a few hundred years vs. nearly a thousand years doesn't make much difference. I'd argue that any territory that has belonged to country X for longer than all of its inhabitants have been alive has a pretty fair claim to be historical territory of country X, and should continue being part of country X unless there's a very good reason otherwise. (Such as a valid treaty, a clear referendum, and so on).

It gets all complicated and messy when war is involved, of course. I'm talking about peaceful transfers of ownership here.

Because the people who live there overwhelmingly (98%–99%) vote in favour of remaining British.

https://en.wikipedia.org/wiki/1967_Gibraltar_sovereignty_ref...

https://en.wikipedia.org/wiki/2002_Gibraltar_sovereignty_ref...