Voted for

• Only London and UK content

If you want a Steemlondon tribe, then this is the only logical answer.
What would be the meaning of a tribe with a certain topic in its name, if you could post all types of content? I mean even completely unrelated ones.
The tribe would be meaningless. The same goes with the topics/tags. They are there for a reason. Let's view this from a different perspective/another point of view:
I think that you would not be happy, if you would like to look for video game related contents, so you would check the "gaming" tag, but you would find completely irrelevant/unrelated contents under that tag, for example food recipes or travel related posts. I mean that the tag would be filled those contents, because people could post "all content". The tag would lose its purpose.
Let's imagine: You would check the Steemlondon tribe, and you would find a lot of content about Finland, Sweden, Russia or anything else, but not (or a very little content about) London and the United Kingdom. So, similarly to the tag with the example above, the Steemlondon tribe would lose its purpose.