Produced specifically for the king or Oba, these ivory pendant masks are testament to Benin's golden age when the kingdom flourished economically, politically and artistically. The face is thought to depict Idia, the mother of the Oba Esigie (c.1504-1550), who was granted the title Iyoba (Queen Mother) in recognition of her help and counsel during military campaigns.
The masks were created at least in part as objects of veneration. The much-admired, time-worn and honey-coloured surface of Sotheby's mask attests to years of rubbing with palm oil.
Only four other ivory pendant masks of this type are known and are in institutional collections - housed in the British Museum, the Metropolitan Museum of Art, the Linden-Museum in Stuttgart and the Seattle Art Museum (the closest to Sotheby's example).
The mask has not been seen for more than half a century.
When Jacob Epstein encountered it in 1947 as part of a loan exhibition at the Berkeley Galleries in London entitled Ancient Benin, he asked the family if he could exchange it for one of his sculptures (an offer they astutely declined). It again formed part of an exhibition in 1951 - Traditional Sculpture from the Colonies at the Arts Gallery of the Imperial Institute - but its whereabouts since have remained unknown until the family contacted Sotheby's last year.
The mask will be sold by the descendants of Lieutenant Colonel Sir Henry Lionel Gallwey (1859-1949), who was appointed deputy commissioner and vice-consul in the newly established Oil Rivers Protectorate (later the Niger Coast Protectorate) in 1891.
Although it was never signed, it was the Gallwey Treaty that became the legal basis for the British Government's controversial Punitive Expedition of 1897, when Benin City was put to the sword and much of the kingdom's art was destroyed looted or dispersed.
Later in 1897 the booty was auctioned in Paris - the beginnings of a long and slow European reassessment of the value of West African art, but also the origins of a case that now parallels that of the Elgin Marbles.
Nigeria, which includes the area of the Kingdom of Benin, bought around 50 Benin bronzes from the British Museum between the 1950s and 1970s, and has repeatedly called for the return of the remainder.
Gallwey (in 1913, shortly before he was appointed governor of South Australia, he changed his name to Galway) remained in Nigeria until 1902 and the exact circumstances of his acquisition is unknown. He is understood to have been given a large tusk by the Oba in 1892, but it is most likely the mask was acquired during the turmoil of 1897.
It comes to auction together with five other Benin objects from the same source. Treasures: Royal Benin Art will also include a bronze sculpture of a type historically identified as tusk stands.
The twisted and hollowed form of this stand (estimate £8000-12,000) suggests it served the same function as the more familiar bronze commemorative heads, as a stand for a carved ivory tusk on an altar created to honour a former ruler.
A tusk made for the altar of an 18th century Oba carved with iconography repeated across many art forms in Benin (including the well-documented bronze plaques) is also included in the February sale estimated at £125,000-175,000.
It is unusual for material of this type to be sold by Sotheby's in London (typically tribal art is sold in Paris), but, according to the auctioneers, the consignor specifically requested its sale in the UK.
By Roland Arkell