Update March 2017: Piano Concerto Found! A wonderful result of researching materials from Jaime's archives for Masaru Sakuma and his doctoral thesis.
1950 Madrid. Rare photo of Jaime (25 yrs old) after conducting the Madrid Symphony Orchestra in a performance of his now lost Piano Concerto No. 1. From Left to Right (front row): Alfredo Sanches Bella, President of the Institute of Hispanic Culture; Enrique Herzog, Bolivian Ambassador in Spain and former Bolivian president; Esther Fernandez, Argentinian Pianist who performed the world premiere of the concerto. Unknown gentleman standing near Jaime (far right) and 2 unknown gentlemen in back row.