He was a member of the Royal Spanish Academy and was also a noted historian; he founded the Real Academia de la Historia in 1735 and became its first director.

While in Majorca, they created some sort of literary academy with the assistance, apparently, of the "Count of Mahon and Colonel of the Dragoon's Regiment of Edinburgh", (???

His deep knowledge of law, French and Italian called the attention of the then powerful PM José Patiño, o (Milano, Italy, 11 April 1666 – 3 November 1736), being promoted to Secretary of the English – Spanish political meetings and truces being discussed there.

In 1734 he married María Josefa Manrique, daughter of General Field Marshal Diego Antonio Manrique, close friend of the Queen Consort and in 1735 he was invested in Madrid "Primer Secretario del Despacho Universal de Estado", (something like the Privy Royal Spanish Council), and on 6 March 1737 he became a Member of the Royal Spanish Academy, becoming a Director on 27 April 1738, publishing in 1739, "Cotejo de la Conducta de S. M. con la del Rey Británico", which could be translated as "A comparison of the behavior of His Majesty against (the behavior) of the British King".

The ailing finances of the Society of History he founded and led came in danger of the eventual closing in 1744 as discussed by Montiano himself and, mercifully, on 25 October 1744, the already seriously mentally deteriorated King "gave notice" of his Royal Approval.