The name Lanihorne is perhaps a modified form of Laryhorn (the Cornish name of this place). The village was, from the mid 12th century onwards, the site of an adulterine castle of the Arcedekne family and the main settlement was at Sheepstor (Sheepstall) some distance away towards Tregony (where the Pomeroy family also built a castle). In 1334 John Arcedekne was granted permission for the castle by Edward III. Before the castle was demolished in the 19th century, it was described as having a 40 ft high keep, seven or eight towers and possibly an outer court.