Rooftop stars

Most of the time I'm going down the Oxford Road I'm driving, in a hurry / stuck in traffic, watching for pedestrians, manoeuvering around buses...and consequently, not looking up!

Today I found myself, for a change, on foot in that part of town. I've glimpsed these figures before, but never stopped for a proper look or had my camera with me.

Now the question that's bothering me is: Why is Joliet Jake the pigeons' favourite?!?