[7] Born in Madrid, Vilallonga – who also went by the surname of Cabeza de Vaca – was a Grandee of Spain and part of the nobility, holding the title of Marquess of Castellbell.

When the Spanish Civil War erupted in 1936, Vilallonga was studying at École Saint-Elme, a Dominican school in Arcachon, but his father ordered him back to Spain to fight on the side of the Nationalists.

His father was an enthusiastic supporter of the rebel side, and at age 16 the younger Vilallonga was a serving member of a Nationalist execution platoon,[8] as a provisional second lieutenant of Requetés.

After World War II, de Vilallonga became increasingly disenchanted with Francoist Spain, and he left the Spanish diplomatic service to live abroad.

He then obtained work as a foreign correspondent for the national press agency EFE and for the magazines Paris Match, Marie Claire and Vogue.

His social connections and ability to relate gossip among Europe's jet set enabled him to regularly sell magazine articles, in addition to authoring four autobiographical tell-all books about his numerous love affairs.

Throughout the late 1950s and 1960s, Vilallonga appeared in numerous films in both Europe and Hollywood, working with prominent directors like Federico Fellini, Agnès Varda, Fred Zinnemann and John Schlesinger.

Though courts twice found him liable for alimony to his first wife Essylt-Priscilla Scott-Ellis, de Vilallonga never paid the judgment, an act which reduced her to poverty for the remainder of her life.