An exhibit of invalid Luxembourg frankings would leave most philatelic judges stupefied. How would they assess the philatelic significance of such material? Would they consider all such uses to be “philatelically contrived?” And what criteria would they apply to the “challenge factor?”
Consider that finding invalid Luxembourg frankings is much more difficult than finding multiples of Luxembourg #1 on cover, and philatelic knowledge is more useful than a plump bank account. But as we should know, philatelic judging is subjective; the equal interval point scale used at the FIP level is illusory. It makes a mockery of the logic of measurement. So don’t necessarily expect to be rewarded with medals when you discover these rarities! Sadly, they are elusive but little appreciated.
After more than 50 years of sniffing through dealers’ junk boxes, my album of invalid uses is still pretty thin. Here is the only example I’ve found of double invalidity:
20c Luxembourg Arms postal card used with a
5+5-pf German Württemberg Arms semipostal,
posted within Germany, July 15, 1927
Luxembourg postal stationery, regardless of validity, of course could not be used within another country. Even the reply cards from double cards had to be returned to their country of origin. But what about the German semipostal stamp? It was issued on December 1, 1926; however, it was only valid until June 30, 1927. Here it is used 15 days too late, on July 15, 1927. Thus, both the Luxembourg postal stationery imprint and the German semipostal stamp are invalid, albeit for different reasons.
Kudos to the sharp-eyed German postal clerk in Karlsruhe who taxed the card double the German domestic postcard rate and marked off both the stamp and the stationery imprint as invalid!