Hi!
I'm a relative newbie here, but I have noted that in the England section of the forum, there are often questions about London and personal safety. I live in London and think it is VERY safe. And so I was pleased to have that backed up by this fun YouTube video from a creator I trust to be rational and fact based.
His brand of snark might not be for everyone here, but he makes some excellent points. If you are headed to London and worried about phone snatchers and crime on the tube and whatnot, I urge you to give this a watch. :-)