Totem poles have their annual clean at the British Museum

In the Great Court at the British Museum, conservator Philip Kevin is suspended 13 metres (43ft) above the ground on a cherry-picker, from which he can reach the higher segments of the Haida totem pole with his cleaning equipment – a low-powered vacuum machine and gentle, conservation-grade sponge Photograph: Graeme Robertson

The Haida pole stands 11 metres (36ft) tall on a 2-metre (6ft 5') plinth Photograph: Graeme Robertson

This taller Haida pole comes from Queen Charlotte Island, off the Pacific coast of Canada. Carved in about 1850 out of red cedar, it was bought from Chief Wiah of Masset in 1903. The smaller pole was carved in the 1860s and comes from the Nisga'a nation Photograph: Graeme Robertson

The two poles were erected in the Great Court in 2007. It takes three conservators eight hours a night, for six nights, to clean the poles and check them for signs of deterioration Photograph: Graeme Robertson