Three 1915 Tanganyika "Mafia Island" issues are the top lots of a sale at Apex Philatelics on March 16.
The one, two and three rupee stamps are to auction in Surrey, UK as separate lots with respective estimates of between £5,500 ($8,982) and £7,000 ($11,431).
They originate from Mafia Island on the Tanzinian Zanzibar Archipelago, which was bought from the Sultan of Oman by the German government in 1890 for the sum of 4m marks.
Mafia Island was used as a port in the Indian Ocean up until it was captured by the British during the first world war, after which the local German East Africa stamps were overprinted with "GR Mafia".
Another example of this overprinted German key type originates from Togo. The 1914 Togo Anglo French Occupation 2m type 1 is offered with a £5,500 ($8,982) estimate.
It dates to the invasion of Togo by French and British forces, which divided the country in two. It bears a rare example of the first French handstamp.
Also featured is a rare inverted 1901 Expo one-cent mint, one of around 100 known to exist. It is expected to realise £3,500 ($5,715).
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