 This has been anglicised as "Ballycashlan-Offerillan" and "Ballycaslane-Offeralane".Uí Fhoirchealláin is the name of the parish and was added to distinguish it from another Castletown.According to an extract from "A Topographical Dictionary of Ireland", published in 1837 by Samuel Lewis, Castletown was then ""a village in the Parish of Offerlane, barony of Upper Ossory, Queen’s county, and province of Leinster, 1 miles (S.by W.) from Mountrath; containing 367 inhabitants.