ET3XY 1957 Ethiopia

Prince Sahle Selassie (1932-1962) was a son of the famous Emperor Haile Selassie of Ethiopia.
Sahle is mentioned in a biography of his father as an active radio amateur who was able
to communicate and relay information during an attempted coup in 1960.

On one of the famous hams sites, his callsign is given as ET3XY. There is a ET3XY card on Ham Gallery from the W4WJ collection.
It gives no identifying details, except at bottom left -
Trent
P.O.Box 849

This card is rather illegibly signed.
These cards are larger-sized, and the writing on the cards is scribbly.
Does anyone have any evidence to link the card/callsign with the Prince ?

Did find that call registered to the Telecommunications Amateur Radio Club, P.O. Box 1047, Addis Ababa.

QSL + Info G4UZN Collection
Article courtesy of N2BTD