Mecca's book - One Stop Short of Barking claims that Waterloo (northbound on the Bakerloo Line) is a particularly good place to spot mice, and says that they are most likely to be found wherever more food wrappers are dropped.
In her book she cites a station assistant announcement to a couple of kids who were peering at some mice on the track:
"'This is an announcement for the two children near the edge of the platform. Please do not stare at the mice under the tracks, as they are in fact Albanian killer mice and very dangerous. Please stand well back from the platform edge'
As the kids stopped looking and sheepishly backed away, the same voice came back over the system: 'This is an announcement for the mice on the station: "Eek, eek, eek, eek, eek!' Thank you"