This carved wooden head is a musu musu or nguzunguzu - an ornament placed on the prow of a war canoe. It is intended to provide protection from wave and wind spirits and to pilot the crew through difficult waters. When used, the ornament would be lashed to the bow of the canoe just above the waterline. 

Carvings of this kind were typically painted black before being inlaid with mother-of-pearl designs mirroring the face-paint of a warrior. They are distinctive for their anthropomorphic forms with protruding mouths and elongated ear lobes.

Presented to Queen Elizabeth II by the Governor-General of the Solomon Islands, Sir George Lepping, during an audience at Buckingham Palace, 11 February 1993.