She is the daughter of Albert Friedrich Paul Freiherr von Westenholz (1921-2011) [1] and Elisabeth Henriette van Hasselt (1927-2014).
De Westenholz studied history of art at the University of Leiden and received her doctorate on a dissertation about her "step grandfather" Albert Vogel sr. (1874-1933), who also was a famous solo actor in the Netherlands.
Later, she co-organized a number of exhibitions about Dutch art in England, one of which took place during the William and Mary celebration year.
As off 1992, she continued to work as a free-lance art historian en writer in Monaco but returned to London a few years later.
On 18 June 2013 she received a Zilveren Anjer (Silver Carnation, the equivalent of a British Companion of Honour) from former Queen Beatrix of the Netherlands for the founding and upkeep of the Louis Couperus Museum.