On her mother's death Lady Katherine's elder sister, Lady Rosamund Agnes (1914–2003) became the 11th Countess of Dysart, but never married or had issue; on her death in December 2003 Lady Katherine succeeded to the titles of Countess of Dysart and Lady Huntingtower.
On her mother's demise, Lady Katherine's elder sister, Lady Rosamund Agnes (1914–2003), became the 11th Countess of Dysart but never married or had offspring; upon her death in December 2003, Lady Katherine inherited the titles of Countess of Dysart and Lady Huntingtower.