[4] He was married to María Trinidad Martos y Zabálburu, Viscountess of Ugena, heiress of a great family fortune and lands in Murcia.

[5] He succeeded first in the title of Count of Tendilla (following the family tradition) and as such enters in January 1955 in the group of people dedicated to the education of the future King Juan Carlos I. Cotoner didn't succeed to the Marquessate of Mondéjar until after the death of his mother, by letter of succession of the 9 of May 1956.

[6] In 1955, he was assigned as preceptor of the then Prince of Asturias, Juan Carlos de Borbón as a horse riding teacher and for his entry into the General Military Academy of Zaragoza.

Don Juan appointed him head of the House of His Royal Highness the Prince of Spain, as heir to the throne in 1964, for eleven years later, on the death of Franco and with the accession to the throne as king of Spain, to be appointed Chief of the Royal House on 2 December 1975, position in which he remained until 22 January 1990, being replaced by Sabino Fernández Campo.

[8] Nicolás Cotoner showed himself to be a man of absolute confidence in the management of the national public interest, standing out during the complicated moments of the transition to democracy and during the failed Tejero coup on 23 February 1981, where maintained an active attitude of support for the king, facilitating contacts between the Crown and the different commands of the army.