I asked Google maps where the nearest toilet was, and was informed there was one right outside Vauxhall station.
This is it:
So basically it's an open-air urinal for the use of people with male hardware. You can see people while you're having a wee and they can see you.
There's something disconcerting about standing there emptying your bladder while thirty people using a pedestrian crossing watch on. Still, if you've got to go, you've got to go.
I don't know why it's open-air, but I guess it needs less cleaning when exposed to the elements.
Also, homelesss people can't sleep there.