H Company [section], 4th Battalion Northamptonshire Regiment (Kelly, 1910)
O Company 1st Volunteer
ds 'C' Squadron Northamptonshire Yeomanry
'The Drill Hall of the O Company 1st Volunteer is in Church street.' (Kelly, 1903)
A site visit in November 2006 did not discover any obvious candidates for the building mentioned by Kelly, so any additional information would be welcome.