Parrots in London

 I remembered the first time I saw parrots in our nearby park, I was sure that it was a pet parrot that had escaped, but then I saw more and more of them, and realised that they must be living here. 

So I went home and looked it up on the internet, and sure enough, there are wild parrots (or parakeets) in London.
But I have now read so many different stories about how they came to live here, that I don't know which one to believe. But the thread in all the stories is, that way way back, a large bunch of them escaped from somewhere, and decided that the climate was good enough for them, so they stayed.