Bute died in 1900 and his widow, the Marchioness, was given a life interest in Castell Coch; during her mourning, she and her daughter, Lady Margaret Crichton-Stuart, occupied the castle and made occasional visits thereafter. Production in the castle vineyards ceased during the First World War due to the shortages of the sugar needed for the fermentation process, and in 1920 the vineyards were uprooted. John, the 4th Marquess, acquired the castle in 1932 but made little use of it. He also began to reduce the family's investments in South Wales. The coal trade had declined after 1918 and industry had suffered during the depression of the 1920s; by 1938, the great majority of the family interests, including the coal mines and docks, had been sold off or nationalised.