He married thirdly at Lugano-Castagnola on 17 September 1956 New Zealand-born British photographic and fashion model Fiona Frances Elaine Campbell-Walter (b. Takapuna, Auckland Region, New Zealand, 25 June 1932). They divorced on 20 January 1965, and she went on to have a well-publicized relationship with Greek shipping heir Alexander Onassis, the only son of Aristotle Onassis. Their children were: Francesca Anne Dolores Freiin Thyssen-Bornemisza de Kászon et Impérfalva (b. Lausanne, 7 June 1958), married at Mariazell, 31 January 1993 to Karl Habsburg-Lothringen, heir to the defunct Austrian Imperial Throne, and had issue Lorne Freiherr Thyssen-Bornemisza de Kászon et Impérfalva (b. Lugano or Lausanne, 15 June 1963), who converted to Islam and is unmarried and without issue; he is the producer and director of Labyrinth (2003) and the executive producer of The Garden of Eden (2008)