Mr. Morgan Williams died at the castle in 1909 and was succeeded by his son Godfrey. It was during his ownership that the castle is said to have been so disturbed by ghostly apparitions and noises that he put it up for sale. These manifestations included : a panther repeatedly seen in the corridors ; a bright light, like a glaring eye, appearing nightly in one of the bedrooms ; a hag of horrible appearance in the armoury and continual piano playing by invisible hands even when the piano was closed. However, an exorcist was persuaded to visit the castle and after he had prayed in one of the rooms a great gust of wind is said to have blown from the room, swept down the staircase, and all but carried the owner of the castle into the garden. The exorcism appears to have been completely successful.
In 1922 the castle was sold to an American, Mr. Richard Pennoyer, whose wife was the Dowager Countess of Shrewsbury, but it was shortly sold to another American who had a far greater effect on it.
Mr. William Randolph Hearst
From 1936 onwards times were financially difficult for Hearst and St. Donat's was put on the market in 1938 after Hearst had occupied it for a bare four months in all. He had spent an enormous amount on the castle, all of which, including the great variety of valuable silver, armour and other things he had in the castle was bought out of the proceeds of his English magazines, primarily, Good Housekeeping. However, war broke out before there was a sale and the castle was requisitioned as an officers' training centre. After the war, it continued to be looked after by the manging director of Hearst's National Magazine Company, in the name of which it had originally been bought.
There were various potential purchasers. Possible future uses included a project for turning the castle into a domestic training college for girls and the last idea was for an extensive caravan holiday camp. Planning permission for this was refused by the Cowbridge Rural District Council and at about the same time the headmaster designate, Rear Admiral D. J. Hoare, visited the castle and saw what a wonderful site it would be for the first Atlantic College. His Council agreed and Monsieur Antonin Besse very kindly bought it for the Atlantic College in 1960.