I lived in London until 2008, and used the tube regularly, there was sometimes buskers in the stations, but that's it really.
My sister and I sometimes visit London, and the last few times we've been, there have been people walking through the carriages begging, they'll sometimes give a speech saying how they're homeless and are grateful for anything that can be given, often looking very dishevelled.
The last time we were on the tube, this man was begging, saying how he'd fallen on hard times, and he hated having to ask for help- everyone in the full carriage just stared straight ahead ignoring him, maybe my sister and I are naive, but we felt so bad for him that we gave him a couple of quid.
So, is this the norm now in London??