A Kenya & Uganda £100 red and black has sold for £120,000 ($181,516) in Spink's sale of the Vestey collection of East Africa stamps in London on January 28.
It realised an increase of 50% on an £80,000 ($125,702) estimate.
The lot was issued between 1922 and 1927 under the rule of the British Empire.
The earliest stamps printed for the region are marked "EAST AFRICA AND UGANDA PROTECTORATES". Kenya would later become a crown colony, resulting in a change to "KENYA AND UGANDA".
The house describes it as "a magnificent showpiece and one of the great rarities of the British Commonwealth."
A 1922-1927 Kenya & Uganda £75 purple and gray also sold well, achieving £85,000 ($128,573) - up 70% on a valuation of £50,000 ($78,564).
An 1891 Mombasa provincial cover bearing a 1 anna on a 4a brown strip of three sold for £19,000 ($28,740).
It was sent from the city by Royal Navy captain FG Dundas to his son, who was billeted on a ship anchored in Malta.
It features various datestamps telling the story of its 3,000-mile journey.
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