Diagonal Paperfold on a 1947 1.50F+50c Caritas!

At Christmas, I enjoy revisiting my covers from the post-World War II era that are franked with the Caritas semi-postals, which appear in December each year.  These stamps were mostly used during the Christmas & New Year's season.  And until the 1986 issue, they were only valid for a short time, usually little longer than one year.  As a consequence, correctly franked commercial uses are well worth pursuing.

The mixed franking seen on the cover shown above correctly pays the 3.50F 20g UPU letter rate from Luxembourg-Ville, January 9, 1948, to Zug, Switzerland.  But what's that white line across the 1.50F+50c Lentz 1947 Caritas stamp?  It's a paperfold, seldom encountered on any of the well executed Caritas sets of the late 1940s and early 1950s, and probably unique on cover.

So along with this engaging cover, I send Christmas greetings and New Year's wishes that you'll make many exciting philatelic discoveries in 2011!