But islanders said they could not call the visit a success unless it prompted more significant change for the community.
Farmer Tony Handerson, who owns 4000ha of land, said the pressures Chatham Islanders faced were often underestimated by politicians.
"They come thinking that the island just needs a kick in the bum, but then they realise it's hard, and there's subtleties under the hood. There's delays, there's high costs, it's different.
"So there's this friction - we call it the tyranny of distance."
Councillor and hardware store owner Monique Croon pointed out that New Zealand recently donated solar panels to Tonga, while the Chathams was still waiting on a remedy for its electricity woes.
The price of electricity in parts of Tonga was now around 58c per kw/hr, compared to $1.02 on the Chathams.
But the staunchly independent residents were not keen on Government hand-outs.
Mr Key spoke of the potential of a new phosphate mining venture on the Chatham Rise, which would create jobs and possibly finance a new port.
Mr Handerson was wary of new ventures after living through several cycles of boom-and-bust industries which usually saw most of the wealth head to the mainland.
But he could not deny the huge potential of phosphate, the main ingredient in fertiliser.
Phosphate has already had an effect on the islands - the pasture near the coast was tinged green because sand containing phosphate was blown ashore.