KEY POINTS:
Four "extraordinary" Maori portrait tiles will go under the hammer at British auction house Bonhams this month.
Up for sale are the ceramic images of Ngati Maru chief Matene Te Nga, Tuari Netana, believed to be another Maori chief, and two women named only as "Bella" and "Sophia".
Few details are known of Tuari Netana, but the women are believed to be the celebrated Rotorua guides Sophia Hinerangi and Bella Papakura.
Guide Sophia is also famous for her role as a rescuer during the Mt Tarawera eruption.
The set of four portraits, taken about the turn of the 20th century, is expected to fetch between £1000 and £1500 ($2850 to $4275).
The image of Te Nga cloaked in a korowai, with a full facial moko, has taken his Taranaki-based iwi Ngati Maru by surprise.
Te Nga is a grandfather of Puti Tipene Watene (1910-1967), a former national rugby league captain, politician and industrial welfare officer.
Ngati Maru chairman Jan Mataku said news of the auction and the existence of the photograph of the revered ancestor came as a surprise.
He said although there was iwi interest in bidding for the tiles, it would require agreement of the board.
"I would like to see all tribal taonga returned to the tribe, but if they are in private hands then the tribe must pay if they want them."
Sarah Shirley-Priest of Bonhams' ceramics and decorative arts department said the portraits were brought in as part of a large collection of at least 400 tiles by a collector who had lived in New Zealand.
The four framed tiles were made by master-craftsman George Cartlidge, best known for his Morris Ware Pottery, in Staffordshire between 1897 and 1924.
They were created using a technique popular at the time, rendering photographs on ceramic surfaces for a three-dimensional image.
The technique involved combining the use of varying mono-chromatic glaze and clay body depths.
Ms Shirley-Priest said photo relief portrait tiles were considered "exceptionally rare" and were a "lost art".
The technique was generally used to feature the great and the good of the time - noted tiles included William Gladstone, Queen Victoria and key World War I military figures.
Bridget MacDonald of Te Papa said the museum did not comment on auction activity as it had potential to influence the price. This month a postcard sized-photograph of 19th-century Ngati Porou leader and colonial soldier Ropata Wahawaha and his second in command, Thomas William Porter, taken about 1870 by George Swan of Napier, sold for $3000 at the Auckland-based International Art Centre.