In 1534,
Sir William Brabazon of Leicestershire was posted to Ireland to serve as Vice-Treasurer. Later, in 1539, after vigorously supporting
King Henry VIII's efforts to break with Rome and the
Dissolution of the Monasteries, Brabazon secured the ownership of the Abbey of St. Thomas, Dublin, whose lands included Killruddery. In 1618, the land was granted to his great-grandson, also
William Brabazon (c.1580-1651) who was made the 1st
Earl of Meath in 1627. The 2nd Earl of Meath (1610–1675) built a new house at Killruddery in 1651 to replace one burned down in the civil war six years earlier. Contemporary pictures show an East-facing building of five bays.
John Brabazon, 10th Earl of Meath, carried out an extensive reconstruction of the house between 1820 and 1830. Architects
Sir Richard Morrison and his son William Vitruvius Morrison were commissioned to build a Tudor Revival mansion incorporating the original 17th-century mansion. The result was a large building, featuring a North-facing entrance with a cupola, behind which clustered a number of wings forming an irregular quadrangle around a central courtyard. The interior of the house originally featured elaborate chimney-pieces by Giacinto Micali, crimson silk damask from Spitalfields, stained glass by John Milner, a domed ceiling by Henry Popje and a drawing room ceiling by Simon Gilligan. A clock tower in the forecourt houses a water clock designed and constructed by
Reginald Brabazon, 13th Earl of Meath, with a pendulum powered by a jet of water.
Reginald Brabazon, 12th Earl of Meath granted extensive use of the site to the
Scout movement for camping, with the
Scout Association of Ireland establishing its training base on the estate at Giltspur Lodge.
Baden Powell visited the house in 1928. From 1952 to 1962, the house underwent a reconstruction, due to severe dry rot. Builders carefully demolished the façade, numbering each brick, and rebuilt a new entrance. and the house was remodeled by
Claud Phillimore The property is managed as a working farm with a number of enterprises used to earn the funds to maintain the estate and provide a living. They operate tours, events, sports, horse riding, festivals, concerts, filming location rentals, farmers market, cafe, and weddings. The working farm produces food for the events and café. ==Gardens==