On August 23, 1978, seventeen days after the death of Pope Paul VI, the Vatican Postal Administration released a series of three stamps to announce the Sede Vacante (Vacant See), also known as the "Interregnum Issue."
After the death of a pope, the throne of the Bishop of Rome becomes temporarily vacant. It remains so until the Sacred College of Cardinals elects a new bishop by means of a conclave. In the interim, the Vatican's secretary of state acts as head of the Church. The See refers to the throne or seat of a bishop. The umbrella over the crossed keys signifies that the "See" is vacant and denotes mourning. When a pope dies, the umbrella replaces the papal tiara on the Vatican coat of arms. After the death of Pope Paul VI, August 6, 1978, Cardinal Jean Villot became caretaker of the Vatican City State for twenty days, until Pope John Paul I was elected (August 26).
A common design was utilized for the three bicolor stamps, consisting of a stylized umbrella over crossed keys. A grillwork background nearly covers the entire stamp. "SEDE VACANTE MCMLXXVII" appears above the design, and "POSTE VATICANE" and the value appear below the design. The lettering and outlines of the emblem and grillwork are printed in lilac on all values. The emblem and background color on each stamp are as follows: 120-lire sky blue, 150-lire pink, and 250-lire light yellow.
The stamps, designed by Italian painter Emidio Vangelli, are vertical in format and measure 25 mm x 40 mm with a 14 x 13 1/4 perforation. The State Polygraphic Institute, Rome, printed 1,300,000 complete sets in rotary photogravure on white glossy paper and distributed them in sheets of fifty.
