The Annseley family had large estates not only in Wexford (main Irish estate, until sold in 1852), but also in Co. Cavan, where they had over 22,000 acres, amongst other places.
Which makes me wonder: If the Reillys were workmen on the Camolin Park demesne, as appears likely, could their ancestor have been brought from Co. Cavan by the Annseleys? An intriguing thought, but there are other Reillys around, so just speculation.