In 1871 Owen was indeed with his grandparents at 'Cottage' Culworth Northants
Source information: RG10/1469
ED, institution, or vessel: 3
Folio: 25 Page: 11
Ann Holliday 60 Bubnell, Warwickshire, England Wife Culworth Northamptonshire
Emma Holliday 20 Culworth, Northamptonshire, England Daughter Culworth Northamptonshire
John Holliday 50 Culworth, Northamptonshire, England Head Culworth Northamptonshire
Owen Holliday 16 Culworth, Northamptonshire, England Grandson Culworth Northamptonshire
and 20 year old lodger Eliza Gascoigne
John and Owen both Ag Labs.
Hope this helps,
Carol