Found most often around Brick Lane, if you manage to find one at all, caliban is the Londoner's term for the young men that act as guides through but especially beneath the city. Most always male, (but there are a few females that fit the term) they seem to know the train tunnels, sewers, and other parts of the city's Underground very very well. Most calibans are thought to be Patteran, but it isn't certain if that's true.