The year 2014 marked the 50th anniversary of the first year of operation of the Germany & Colonies Philatelic Society following the amalgamation of the Germany & Colonies Stamp Club (established 1947) and the Stockton German Study Group (1960).
The G&CPS celebrated its inaugural year in 1964 with the first Germania Posta philatelic exhibition held in Stockton.
http://sammler.com/bm/arge_danzig/index.html
http://www.danzig.org/page3-freie-stadt-danzig.html
The above links may prove interesting for those collectors of Danzig who speak German.
kind regards
Nigel