This photo, from the National Library of New Zealand, was taken in 1900, the year before New Zealand unilaterally annexed Niue. King Togia of Niue was a cousin of King Tupou I of Tonga.
According the New Zealand’s Ministry for Culture & Heritage this was the context for the trip:
Even as a fledgling British colony, New Zealand turned its gaze towards the Pacific. From the 1840s, early New Zealand politicians such as Sir George Grey (1812–98), Sir Robert Stout (1844–1930) and Sir Julius Vogel (1835–99) actively promoted a vision of New Zealand as the centre of a great South Pacific empire.
As a small, remote and under-populated British colony, New Zealand was vulnerable. It wanted economic stability and security against invasion. It wanted Britain to extend her control of trade routes and prevent rival imperial powers such as France and Germany from increasing their influence in the region.
Grey, Stout and Vogel advocated ambitious policies of expansion in the Pacific. But their persistent calls for British annexations in the region, particularly of the larger island groups of Samoa and Fiji, were rejected by London’s reluctant and often dismissive Colonial Office.
During the 1890s, Premier Richard Seddon (1845–1906) actively promoted New Zealand as the ‘Britain of the South Pacific’. Like those before him, ‘King Dick’ believed that New Zealand’s geographical position and its experience governing Maori made it ideally suited to administer other Pacific territories on behalf of Britain.