Their names are all taken from places in Yorkshire. Tim Firth said about how he named the Rottentrolls: "I put a compass in the OS map of the area, centred on Troller's Ghyll and drew a circle of about 5 cm radius. I then harvested the strangest-sounding villages and geographical features. These then seemed to suggest, bizarrely, the colours of various mad characters. Yockenthwaite would clearly be an idiot because it had a 'k' in it. Sigsworthy Crags would clearly be off his trolley, but older. Penyghent would be female... and so on. I wish every assembly of characters was that easy."