From American Philatelic Society (https://stamps.org/HOF-2000):
"Dr. Diena was an internationally renowned philatelist who was an editor, writer, expert, judge and collector. He was the third generation of acknowledged experts on Italian philately, beginning with his grandfather, Dr. Emilio Diena, over a century ago and continued by his father Alberto and uncle Mario.
Diena began his philatelic career as World War II ended. His first important position was in 1951 as editor of Italia Filatelica. This publication soon merged with the weekly La Settimana del Collezionista to form Il Collezionista - Italia Filatelica, Italy's most popular stamp journal. He continued as editor for 17 years. He also edited the first three years of the Bolaffi Catalog of Italian Stamps (1956-58), and continued as an advisor to the catalog's publisher for the rest of his life. He wrote prolifically on Italian and Italian States stamps, and worked on the Diena expert committee with his father and uncle. Enzo was a founder and president of the International Association of Catalogue Publishers (ASCAT) and served as president of the International Association of Philatelic Expertisers (AIEP).
In 1959 Diena served on his first international jury, and for the next 40 years his command of five languages and his very broad philatelic knowledge, made him a popular choice for international juries. He was a juror for nearly every international philatelic exhibition during that time, often serving as secretary or president.
His philatelic expertise led to his becoming a member of the Philatelic Committee of the Italian Ministry of Posts, and his knowledge of printing led to his serving with the Poligrafico dello Stato (State Printing Works).
Diena signed the Golden Roll of Italian Philately in 1967. He signed the Roll of Distinguished Philatelists in 1977, following his grandfather Emilio, who was one of the RDP founder signatories in 1921, and his uncle Mario who signed the RDP in 1956. He also received the Lichtenstein Medal in 1978 and the Luff Award in 1981 for Exceptional Contributions to Philately. The Berlin Philatelic Club awarded him the Lindenberg Medal in 1984."
Elected to membership of RPSL in 1972, became a Fellow in 1975 and left/died in 2005.