A History of the County of Buckingham: Vol 3 (1925) contains the following reference:
Among the Bishop of Winchester’s documents (now in the hands of the Ecclesiastical Commissioners) are rent rolls of the manor of West Wycombe, dating from the year 1207 onwards.
The manor and parish (of West Wycombe ed.) were coterminous, and from the earliest time the estate was divided for administrative purposes into ten tithings. The tithing of Bokar, still marked by Booker hamlet and common in the south of the parish, is named in the early 13th century and also in the transfer of the manor in 1706. A fourth tithing is that of Downley, still existing in the north-east of the parish.
NB Historically a tithing refers to ‘a group of ten households who lived close together and are collectively responsible for each others behaviour’.