Apparently #BLACK_LIVES_MATTER protests have made it London today. I know there's more planned for tomorrow, and on the 3rd and 7th. If you want to be there keep an eye on the tag #LDNBLM
(to be clear, I'm not an organiser or a spokesperson so don't take me as an authority. I'm just passing on what I've seen because I know not everyone will know).
I'll put some info in the rest of this thread about possible protests I've seen talked about. These graphics aren't mine and I can't give you any more info than what they say so make sure to look into it yourself using the tag but it should give you an idea.