In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Harrowby like this:
HARROWBY, a township in Grantham parish, Lincoln; adjacent to the Grantham and Nottingham canal, 1 mile W of Grantham. Real property, £3, 072. Pop., 118. Houses, 19. The manor belonged to the Rolts; passed, about the middle of last century, to the Ryders; and gives them the title of Earl. Harrowby Hall was formerly the seat of the earls, but is now otherwise occupied.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Harrowby has changed, please see our redistricted information for the modern district of South Kesteven. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Harrowby and units named after it.
GB Historical GIS / University of Portsmouth, History of Harrowby, in South Kesteven and Lincolnshire | Map and description, A Vision of Britain through Time.
Date accessed: 26th May 2016
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Harrowby".