In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Armston like this:
ARMSTON, a hamlet in Polebrook parish, Northampton; near the Peterborough railway and the river Nen, 3¼ miles SE of Oundle. Pop., 26.
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 Armston has changed, please see our redistricted information for the modern district of East Northamptonshire. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Armston and units named after it.
GB Historical GIS / University of Portsmouth, History of Armston in East Northamptonshire | Map and description, A Vision of Britain through Time.
Date accessed: 08th December 2013
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Armston".