John Bridges began collecting material for a history of the county in 1719, in which year he and
a helper visited the parishes in this area; their manuscripts are now in the Bodleian Library.
Only in 1791 did Peter Whalley publish an edited version in two volumes. Kelly's directories,
begun in 1847, gave some topographical information, and the 1847 and 1928 editions have been
used. Francis Whellan edited a history and directory of the country in 1849; the revised edition of
1874 has been used. All of the area except the five westernmost parishes in Corby Hundred was
included in the second volume of the Victoria County History in 1906. The most important
modern work on the area is P. A. J. Pettit's The Royal Forests of Northamptonshire, 1558–1714,
published in 1968. These books are the main printed sources used for the parish introductions in
this Inventory. Population statistics have been taken from the Hearth Tax of 1673, from Bridges
for 1719, and from the censuses from 1801 onwards.
Most of the manuscript material for the area is in the Northamptonshire Record Office,
including probate inventories from wills proved at Peterborough, enclosure and other maps,
family archives from Apethorpe, Bulwick and Duddington, and post-Reformation ecclesiastical
records. Before the 16th century the area was in Lincoln diocese, and the records are in the
Lincoln Archive Office. The Exeter estate papers are at Burghley House and at the Burghley
Estate Office, Stamford. The pencil sketchbooks of George Clarke (1790–1868) held in the
Northamptonshire Record Office give information as to the appearance of churches and some of
the larger houses in the 1840s and the drawings of Gilbert Flesher (c. 1758–1831) which form BL
Add. MSS 37411–37413 depict the churches at the beginning of the 19th century.