In the early nineteenth century missionaries were trying several different methods of converting local Māori to Christianity. According to Vincent O'Malley's The Meeting Place: Māori and Pākehā Encounters, 1642 - 1840 they were placing a lot in the strategy  of taking influential Māori and showing them firsthand the wonders of Christian civilisation overseas.

Tuai and Titere were two chiefs from the Bay of Islands who had been to Parramatta with Marsden and were whisked away to England. Their escort was Francis Hall who was no doubt pleased when the two chiefs had pledged to follow Jesus and adopt the British way of life.

However, once back in Aotearoa Hall reported both men had returned to their ways of "Sin and Satan ..." and sowed ".. no disposition to persevere..." in their study of the bible. 

I like imagining how these two guys from the Bay of Islands scored a free trip to England and how they might have sucked the marrow of the place dry as only a pair of twenty year-olds can. I'm pretty sure if someone offered me an all expenses paid trip to London at that age I would have told them anything they wanted.