/revised 24 Aug 2009
T 18c, "c" 5x1.5 mm
Flower pot 17.5x19.5 mm
Colour: Violet
We have recently found that there are two types of this marking. The items registered 1953-55 may be of the other type with wider more rounded "c"
Items known:
10.3.1953 Stockholm via ? to Taormina (IT), violet
1955 Göteborg to Ireland
27.8.1962 Göteborg to Bonn (DE), violet
13.11.1963 Göteborg 5 to Genève (CH), violet
7.2.1964 Göteborg to Genève (CH), violet
13.2.1964 Göteborg to Camebridge (UK)

7.2.1964. Single letter rate to Switzerland. Correct rate 50 öre. Shortpaid 15 öre. Amount due 2x15/1.70=18 centimes (gold). At this time Switzerland did not use the UPU rule for postage due on incoming mail. Instead, between 1 Apr 1959 and 1 Jan 1966, the amount due was calculated as the double amount missing in the sending country divided by the foreign letter rate in the sending country multiplied by the 7/10th of the Swiss foreign letter rate rounded up to nearest 5 centimes. For this letter it would be (2x15 öre/50 öre)x(7/10)x50 Swiss centimes = 21 ~ 25 centimes. (Litterature: Schweizer Briefmarken Zeitung 2003:10 p. 348-351)