London apparently has a high density of them (but high density still only means something like 40 breeding pairs), and some people are all excited about the prospect that they can do something about the rapidly rising wild parakeet population...
I'm having a hard time squaring away the image of grey gloomy London also being overrun with colourful tropical looking birds, I had to google it and see.
Here are some pictures taken out of my home office window too:
https://m.galaxybound.com/@vidar/114256153547342202
And a short walk from mine:
https://m.galaxybound.com/@vidar/114582595390607406
They're everywhere at this point.
They’re surprisingly well adapted to a large range of temperatures because of the species found in temperate rainforests at higher altitudes. They frequently enough escape from pet stores and zoos that there are many sizable populations spread out around the world. The one nearest me is the infamous Pasadena parrots [1] which is made up of thousands of birds likely built up over decades of escapes. There are populations in Chicago, New York, Rome, Tokyo, and plenty of other cities in the world.