The decisive development came with the meeting of the first international Postal Congress at Bern in 1874, at the suggestion of the German government. The Bern Congress was attended by delegates from 22 countries: 20 European countries (including Russia), Egypt, and the US. The congress adopted a treaty concerning the establishment of a General Postal Union—commonly known as the Bern Treaty—signed on 9 October 1874. This was the forerunner of the series of multilateral Universal Postal Union conventions and came into force in the following year, when the union was formally established, on 1 July 1875, to administer its operative regulations.
The 1874 Convention provided for subsequent postal congresses to revise the convention in the light of economic and technical developments. The second congress, held in Paris in 1878, changed the name of the General Postal Union to the Universal Postal Union (UPU). Four more congresses were held prior to World War I: 1st in Lisbon, 1885; and 2nd in Vienna, 1891.
The second one held in 1891 in Vienna is of importance. This where the UPU addressed how to frank mail when the mail is sent or posted while the individual is traveling on board a shipping vessel. Which country's postage stamp was to be used? To make it easy, the origin country of the ship or the Flag that it represented was chosen as the default country whose postage stamp would be accepted. The mail would then be transfered to next port where it would dock without incurring any mail forwarding charges.
However, it did not answer the question as to how to identify the franking or cancellation of any mail that originated from on board a ship. So, in 1894 a tentative agreement was reached to use "paquebot" cancel or marking on the mail to distinguish it's use. This was not ratified as official maritime correspondence marking till the 3rd congress session held in Washington, 1897.
Paquebot means Packet Boat in French, since it was the official language of UPU.
Here's the million dollar question, what's Gandhi got to do with Paquebot?
Well, Gandhi traveled to London on S.S. Rajputana to attend the Round Table Conference. No known mail sent by Gandhi and mailed from S.S. Rajputana is known to exist. However an example of a Paquebot cancel from Rajputana, dated 16-Dec-1930 is attached.
After many years I did finally come across a Gandhi Stamp actually used on a Paquebot Cancel. For now I am attaching the scans of both front and the back. I will provide some additional details on the cover at a later point.
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