A Vision of Britain through Time provides the following description of Willybrook Hundred from John Marius Wilson's Imperial Gazetteer of England and Wales of 1870-72:
- "WILLYBROOK, a river and a hundred in the NE of Northampton[shire]. The river rises near Rockingham; runs 10 miles north-eastward to Kingscliffe; and goes thence 5 miles south-south-eastward to the Nen, near Fotheringhay. The hundred contains 14 parishes. Acres: 27,490. Population: 6,995. Houses: 1,476."
Willybrook Hundred is not covered by the Victoria County History of Northamptonshire. For a map of the hundreds of of Northamptonshire, see A Vision of Britain through Time.
List of Parishes
Parish | Description | Notes
| Apethorpe | parish (ancient), civil parish |
| Collyweston | parish (ancient), civil parish |
| Cotterstock | parish (ancient), civil parish |
| Duddington | chapelry, civil parish |
| Easton on the Hill | parish (ancient), civil parish |
| Fotheringhay | parish (ancient), civil parish |
| Glapthorn | chapelry, civil parish |
| Kings Cliffe | parish (ancient), civil parish |
| Lutton | parish (ancient), civil parish |
| Nassington | parish (ancient), civil parish |
| Southwick | parish (ancient), civil parish |
| Tansor | parish (ancient), civil parish |
| Woodnewton | chapelry, civil parish |
| Yarwell | chapelry, civil parish |
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