Huntingdonshire, to the east by Bedfordshire, to the south by Buckinghamshire and Oxfordshire, to the west by Warwickshire, to the northwest by Leicestershire and to the north by Rutland.
The county town is Northampton.
For additional information see Wikipedia and GENUKI:Northamptonshire
There is limited coverage of Northamptonshire in the Victoria County History series. See Britsih History Online for details of volumes 2, 3, 4 & 5 (accessed August 2017)