Baudouin caught my eye in the Trusty Book of Stamps for the simple reason that he’s wearing glasses. You don’t get many spectacles on stamps so that was enough to send me investigating.
Baudouin was King of Belgium from 1951 – 1993. He succeeded his father Leopold III, whose reign was patchy to say the least due to his response to the Nazis. Baudouin came in as a young king (21 years old, about the same age as Elizabeth II when she came to the throne in 1952) and seems to have been pretty popular at home.
He faced greater scrutiny abroad particularly in his relationship with Congo which was seeking independence from Belgium at the time (The Trusty Book of Stamps has Belgium on page 6 and Belgian Congo on page 7, showing that the colonial power relationship gets great respect than the alphabet). Baudouin managed to repeatedly insult Congo and its leaders.
Baudouin died suddenly in 1993 and was succeeded by his brother Albert.