The first mansion at Cwrt yr Ala was built by Robert Rous in 1805. In 1807 it was described by Benjamin Heath Malkin as ?an elegant villa, in a most delicious retirement, belonging to Mr Rous. It has lately been laid out and completed. Any thing more beautiful, on a small scale, cannot well be conceived.? (The Scenery, Antiques and Biography of South Wales, Vol I p206.)

After Robert Rous? death, Cwrt-yr-ala passed to his nephew, Thomas Bates Rous, who in turn bequeathed it to his son Col. George Grey Rous. Col. Rous? sister, the next owner of Cwrt-yr-ala, married that Rev. George Gore. In the years between 1908 and 1937 the Gores let the house to W. H. Brain, the cricketer and owner of the famous Cardiff brewery, until Sir Herbert Merrett bought the house, contents and 1250 acre estate from the East Anglian based Gores in 1937.

Sir Herbert, chairman of the coal conglomerate, Powell Duffryn, and owner of Cardiff City F. C., demolished the old Regency villa, by now on 6 different levels, completing the new 2-storey, white stucco, U-shaped, 7 bedroom house designed by Sir Percy Thomas, just north of the foundations of the old house by September 1939.

Within a year the building was requisitioned by the RAF and used as accommodation and headquarters for a Decoy site built in the adjacent Bullcroft valley (known as the Lawns) to distract nazi bombers from the main Cardiff valley area and to drops their bombs on the estate instead.

On Sir Herbert's death in 1953, the house passed to his daughter, Joan Gridley. That family restored the adjacent lakes and weirs before selling the mansion and 792 acre estate in 1973 to Rivlin Lewis Partners, who in turn sold the house and immediate 40 acres to a Cardiff solicitor, Leighton Loughor in 1976. In the early 1990s Lougher sold to Mr J Gardner, a Cardiff credit card manufacturer who put the house up for sale in summer 2005 for £2.5 million.

(Information from Christoper Gridley, former chairman of the Cwrt-yr-ala Estates Company and resident at Cwrt-yr-ala between 1944 and 1972.)