Luxembourg airmail within Europe: May 1, 1939 to the October 1, 1940 required use of Reichmark franking

 

Effective May 1, 1939, foreign (Belgian, French or German) franking was no longer required to pay international airmail supplements on airmail originating from Luxembourg. 

And, according to the Basien-Hoffkamp rate book at p. 173, from that date forward there were only two rates for airmail to other European countries:

• 50c per 20g for letters to Germany, France, Great Britain, the Netherlands, and Switzerland
• 75c per 20g for letters to all other European countries

The first two covers illustrate these rates.  The rating of the third is a mystery.

Airmail to France
24 Jul 1939

50c airmail supplement

Luxembourg-Ville, July 24, 1939, to Nice, France, July 26, 1939, properly rated at the 20g letter rate to France (1.25F) plus a 50c airmail supplement.

Censored Airmail to Finland
31 Jan 1940

75c airmail supplement

Luxembourg-Ville, January 31, 1940, routed via the Netherlands and Sweden, from the Finnish consulate in Luxembourg, censored in Finland, with February 1, 1940 Brussels transit and February 6, 1940 Helsinki backstamps.

The cover is properly rated at the 20g UPU letter rate (1.75F) plus a 75c airmail supplement.

Officially Resealed Airmail to Italy
13 May 1939

Rate ???

Luxembourg-Gare, May 13, 1939 (less than two weeks since the abolition of the foreign-stamp surcharges), routed in manuscript “Via Cologne,” to Merano, Italy, May 17, 1939, with a strip of four official seals reading “Amministrazione delle Regie Poste,” each dated May 17th [Drummond Type OS2].

Here the franking totals 3.75F.  As a 20g UPU letter, 2.50F would have paid postage and the airmail supplement, with the letter overfranked by 1.25F.  As a 20-40g UPU letter, 4.25F franking would have been required [1.75F + 1F + 75c + 75c], leaving the letter underpaid by 50c. 

Is the letter incorrectly franked?  Somebody must know, and I hate to describe a lovely cover as “misfranked.”