The modern parish of Horne is only the latest of a number of areas with the name: a name that has been applied to ecclesiastic and administrative parishes and to a manor that preceded the parish. The extent of each has varied considerably.
The earliest reference to Horne by name is in the 12th century but it is quite likely that the 1086 reference in Domesday Book to an unnamed half hide held by Roger d'Abernon, under the manor of Chivington, is to land in Horne. This may be to the farm later known as Bysse Court that seems to have become a sub-manor of Bletchingley.
The name itself is thought to mean 'hill or projecting spur of hill' the latter being apposite to the part of the parish near the church perhaps. This is not very obvious unless the church, and presumably the early settlement, is approached from Outwood Common to the north, as it is likely to have been in early times.
Horne did not become a parish in its own right until 1705. Prior to that although it had its own church since at least the 12th century, it had been a chapelry of the parish of Bletchingley. The church at Horne served the southern parts of Bletchingley enabling local people to attend church regularly without having to go to Bletchingley itself except for christenings, marriages and funerals which were retained by the mother church, no doubt for financial reasons. In 1705 the southern part of Bletchingley parish became the new parish of Horne, the new boundary being drawn along Gay House Lane.
The historic parish of Horne did not originate as a single manor as is the case in many places. In places in the deep Weald such as Horne the land was often divided between a number of manors, a situation originating in the period of Saxon settlement when isolated grazing rights became acquired by settlements far away to the north of the downs. When the parishes were set out, probably in the late 12th century, a pragmatic view was often taken and boundaries were drawn in a way convenient to an existing church rather than to ownership of the land. The historic parish of Horne comprises two sub-manors of Bletchingley, Horne itself and Bysse Court and a part of Hedgecourt, a sub-manor perhaps associated with Godstone. Hedgecourt manor, apparently largely a park, stretched from Snow hill (Snowerhill) on early documents to Wiremill and across the county boundary into Sussex.
The present civil parish of Horne includes, on its eastern edge, part of Tandridge manor. This manor was only two fields wide. Its historic boundaries coincided with property boundaries in the 19th century as they must have done when the manor was established perhaps 1000 years ago. In between this and historic Horne is part of Godstone manor.