If there's one thing this thread has demonstrated it's that the forum knows every inch of London, so I don't think there's such a thing as a tag which is too hard.
I do think that when the game stalls, it's nice to keep drip-feeding clues. It's quite infuriating (in a good way) when you know one which nobody else seems to know, but you can't get to it and you're helpless as you see the clues just keep dripping out until someone else nabs it.
If there's one thing this thread has demonstrated it's that the forum knows every inch of London, so I don't think there's such a thing as a tag which is too hard.
I do think that when the game stalls, it's nice to keep drip-feeding clues. It's quite infuriating (in a good way) when you know one which nobody else seems to know, but you can't get to it and you're helpless as you see the clues just keep dripping out until someone else nabs it.