I suppose you have the plane opts?
Yugoslavia
Government in Exile
Stamps of 1943 Overprinted “1945” Aeroplane and both.
Overprinted in London
The overprinted stamps never enjoyed postal validity
A further set exists with opts in gold.
The basic stamps were valid on ships of the Yugoslav Navy, and mercantile Marine.
They exist in Minisheet or Souvenir sheet form.
Celebrating the 25th anniversary of foundation of Yugoslavia
SG0476 (1943) T112 01d v vodnik poet
SG0477 (1943) T112 02d petar njegos poet
SG0478 (1943) T112 03d ljudevit gaz writer
SG0479 (1943) T112 04d vuk karadzic poet
SG0480 (1943) T112 05d bishop strosmajer politician
SG0481 (1943) T112 10d djordje petrovic karageorge
Some debate surrounds the history of these.
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...actually those overprints are locally know as "London issue", as they are made for gov't in Exile only.
Main set is from 1943 year, no overprint, Michel catalog number 445/450 and option exist also in m/s format under
Michel number Block 2. All the overprints are made, but never used, and it is overprinted with AirPlane, in Black and in Gold.
My personal experience are very "strange", because for around 35 year, as part-time stamp dealer, I saw just
once, this set in used condition, and it is just CTO, so, one really fascinating issue and printing that can just
improve any serious collection of Yugoslavia!