Theobald Dillon and his successors acquired an estate of almost 3,000 acres, mostly in Co. Mayo. Theobald, an adventurer, worked for the expansion of Elizabethan control in Connaught and gained immense personal benefits from it. Later generations of the family supported the Catholic cause. The second Viscount, Luke, was a member of the Confederation of Kilkenny. His brother, Louis, who was a Francisan Friar, became Bishop of Achonry (1641 – 1645). Another brother, James, went to France, where he founded the Dillon Regiment.
The Dillons became absentee landlords in the mid eighteenth century, when the Eleventh Viscount married an English heiress. A number of land agents administered the estate. The most notable were Jerrard Strickland and his son Charles. Loughglynn House was built by Richard, 9th. Viscount Dillon, between 1713 and 1737. It belongs therefore to the early phase of mansion building that followed the Williamite Wars. It is Palladian in style and originally had a Mansard roof.
The top storey was removed following a fire in 1896. A demesne was planted in 1801. This consisted of 80 acres of woodland. Three avenues led to the house. The principal one stretched for more than mile to Moyne Crossroads. At the end of the last century, the house was sold and acquired shortly afterwards by the Franciscan Missionaries of Mary, who were noted for their "Ateliers" (industrial schools) in France