Redonda, in the Leeward Islands of the West Indies, was for a time a British possession (though was

Redonda, in the Leeward Islands of the West Indies, was for a time a British possession (though was named Santa Maria de la Redonda by none other than Cristoforo Colombo hisself) used pretty much exclusively for harvesting the guano found in copious amounts on this tiny (one mile long, a third of a mile wide) Caribbean island (closest neighbor is Montserrat; next closest is Nevis; but legally, these days, Redonda is part of Antigua and Barbuda).  When the guano industry declined, the few workers who stayed on the islet departed and Redonda is now considered uninhabited, though that hasn’t stopped the ongoing succession of the Redonda monarchy - yes, the Kingdom of Redonda was first described by novelist M. P. Shiel, who claimed his father conceived of the idea in 1865 (the year M. P. Shiel was born), and since his (Shiel’s) 15th birthday and concurrent ascent to the throne, the kingship has been passed down, generally not through a blood tie but through a kinship of letters, from one writer to another.  This has, perhaps naturally, led to a number of pretenders to the throne and there are currently various claimants to the throne of Redonda.  Presumably needless to say, any postage stamps issued from Redonda are not considered legal philatelically, what with one of the ostensible requirements for legal stamps is that they’re used by people for sending mail - difficult on an uninhabited islet.

Stamp details:
Issued in: 1981
From: Redonda, 
MC #N/A

Recognized as a sovereign state by the UN: No
Claimed by: Antigua and Barbuda
Member of the Universal Postal Union: No