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.
I have acquired a cover that has a black triangle stamped on it with the number '29'. I have enclosed a scan of the cover. The stamp was added after the machine meter mark was applied. Can anyone tell me the meaning of this triangular stamp?
Thanks
Bob