Knapton is a townland in Abbeyleix parish. In Griffiths Valuation for 1850 there were just 5 households listed. The largest by far was that of Wm Brownlow Esq who had a farm, offices (outbuildings) and 127 acres. That seems the most likely property for your ancestors to have worked if they were servants. The Brownlows had left by the time of the 1901 census.
Knapton today is off the R433 south of Abbeyleix town.