Using indexes such as the International Genealogical Index (IGI), it soon becomes clear that the surname is most common in North Wiltshire. The earliest parish register entry so far discovered is in Heddington, Wiltshire in 1541, just a few years after the keeping of parish records began. The family has tended to remain in the south of England and Wales so that even by the time of the census in 1881 only the counties of Breconshire, Berkshire, Buckinghamshire, Cardiganshire, Devonshire, Essex, Glamorgan, Gloucestershire, Hampshire, Kent, Lincolnshire, Middlesex, Monmouthshire, Norfolk, Oxfordshire, Staffordshire, Surrey, Sussex, Wiltshire and Worcestershire in England and Wales have entries for Lanfears.
Most of the Lanfear entries in the General Register Office records of births, marriages and deaths in England and Wales from 1837 to the 1990s have been extracted. The geographical distribution of the entries is plotted on a map.