This Slate article has a collection of photos of "bum-free" additions to buildings and structures in public areas intended for the same purpose as the controversial "homeless deterrent" spikes in a London apartment block (the ones pictured below). Apparently they're a pretty common thing.
In Manchester I recall seeing shards of glass embedded in the tops of walls on a regular basis. Less obviously aggressive are dividers in public benches which make it possible to sit but not lie down. As you can see in the article, a lot of creative work has been put into making it impossible for people to sleep in public areas-- I wonder if that's actually someone's full time job. How depressing an occupation would that be? Does this person have any friends?
Some of my friends have posted approvingly an article about a group of activists who decided to pour concrete over the anti-homeless spikes in a shop window ledge at a Tesco Metro, which apparently resulted in the company agreeing to remove the spikes. First, however, they'll have to remove the concrete. I can't imagine that will be easy. It's a mess which doesn't look any better to sleep on than the spikes, quite frankly.
Tesco, for its part, claims that the spikes were there to inhibit "antisocial behavior" which customers had been complaining about, basically drunken loitering, and weren't intended to be anti-homeless at all. But obviously the effect is the same.
Still, to you well-meaning activists and supporters of activists out there....try talk before property damage, okay? And try thinking for a good while before that.
This is a bigger problem than a few doorways in London. And businesses aren't wrong for not wanting homeless people sleeping on and around their premises, though their methods of dealing with that are sometimes deplorable. When I first saw the doorway pictured below, it occurred to me that if the apartment block had installed a bike rack in that space instead, the same goal would've been accomplished without any of the outrage. And yet the effect would've been the same for any person who had wanted-- no, let's rephrase for accuracy-- felt forced to sleep there.
So on the whole, it's good that these spikes are getting attention because the homeless need attention. But the businesses aren't the villains in this story (at least, not the only ones) and it's going to take a lot more to solve this problem than railing against its symptoms.
I suggest focusing on positive approaches. Here's a good example.