[1] Though his work was not very popular during his lifetime, after his death, a tribute exhibition was devoted to him in the Biblioteca Nacional de España in Madrid.

Invited by friends Enrique Fernández Arbós and Isaac Albéniz, and following the advice of Haes, Regoyos visited Brussels in the following year.

He studied at the Académie Royale des Beaux-Arts and lived in the Belgian capital for ten years, his patron being Edmond Picard, who introduced him to the thriving art world in Brussels.

[2] Regarding his 1912 oil on canvas, Le Poulailler ("The Henhouse"), José Ortega y Gasset said that Regoyos "seemed to kneel to paint a cabbage".

Though his work was not very popular during his lifetime, after his death, a tribute exhibition was devoted to him in the Biblioteca Nacional de España in Madrid.

[8] In his early stage, Regoyos' painting evolved from Naturalism to pre-symbolism, an example being his series The black Spain, to Impressionism and Pointillism, being somewhat more daring than Ignacio Zuloaga and Joaquín Sorolla.

In his mature stage, he created abundant landscapes en plein air of locations of Vizcaya and Guipúzcoa.