Thanks guys
"Concrete Monsters" was just done in about an hour, quite a while ago. I forgot about it until recently. Although it is made up of very different sounds to the other two, I think it should fit in.
Sheffield is a mix of ugly old buildings and ugly new buildings. It does have some nice ones though! Anyway walking through town one day I thought about how these huge things that seem to follow you everywhere can be a bit like big monsters... in a quirky sci-fi kind of way!!
Personally I'm very pleased with "When The City Sleeps". I've still got more work to do on "Empty Streets"... tidy up some of the notes and try adding a new section to break it up a little.