In 1830 he visited the Bay of Islands and bought 220 acres (0.9 km2) of land from Pōmare II[2] and Kiwikiwi, of Ngāti Manu, at Okiato, a few miles south of Kororareka.
[3] Clendon purchased the schooner Fortitude and, with his family and business partner Samuel Stephenson, sailed back to New Zealand in 1832.
He settled on his property at Okiato[2][3] and established a successful trading station supplying whaling ships working in the Pacific Ocean.
His friendship with Pōmare II, Tamati Waka Nene and other Maori chiefs and his contact with the European settlers at Kororareka made him more influential than the British Resident, James Busby, at Waitangi.
[2] Despite representing the U.S., he assisted Captain William Hobson in negotiating the recognition of British sovereignty over New Zealand and was a witness to the signing of the Treaty of Waitangi in February 1840.
[2][3] Felton Mathew, the Surveyor-General, selected Clendon's Okiato property as the most suitable location in the Bay of Islands to establish the capital of the colony.
[7] The Clendon family papers, including material written by his wives, were archived by Heritage New Zealand and Auckland Libraries.