Spoilers for Torchwood 2x04 "Adam"
http://www.bbc.co.uk/torchwood/sites/episodes/series2/ep05_trail2.shtml The cry of those 'horrible creatures' sounds awfully like the Reapers from Doctor Who 1x08 "Father's Day"
However, if Reapers are around, they seem to be meant to devour everything, so they wouldn't have ever 'passed over'?
I'm interested to hear your thoughts.