Great Britain 1922 KGV 9d Mauritania Archive Specimens, Unique

MAURITANIA UPU ARCHIVE RECEIVING AUTHORITY SPECIMENS: 1922 KGV 9d olive-green wmk Royal Cipher (SG 393a). The only such definitive issued between 1917 and 1922. A pair and a single affixed together to portion of ledger page, without any specimen defacements, subsequently handstamped with large part 3-line "SPECIMEN / COLLECTION / MAURITANIE" in red-purple. Sent from the UPU in Berne to the Mauritania Post Office where they were affixed to the ledger page and tied by the Mauritania handstamp. Unique and philatelically important item proving distribution of this, the sole produced value of this series in the 5 year period, in normal unused and undefaced state as specimens through the UPU.