One theory focuses on a local myth, which told how a spirit left a nearby mountain, flew to a distant land and married a queen.
The pale-skinned son of a mountain god had ventured across the seas to look for a rich and powerful bride.
Anthropologists believe Prince Philip became linked to the legend in the 1960s when Vanuatu was an Anglo-French colony known as the New Hebrides.
Villagers at the time were likely to have seen portraits of Prince Philip and the queen at government offices and police stations.
The cult grew with Prince Philip's visit to Vanuatu in 1974, when he appeared in his white naval uniform.
Prince Philip sent the villagers three official portraits over the years, including one of him posing with a nal-nal war club they had sent him.
Villagers prayed to the prince daily, asking for his blessing on the banana and yam crops that make their primitive and extremely poor community self-sufficient.
“If he comes one day the people will not be poor, there will be no sickness, no debt and the garden will be growing very well,” said village chief Jack Malia in 2017.
But now Mr Huffman believes the islanders may turn to Prince Charles as the successor to Prince Philip – at least according to the cult.
This browser does not support the video element.
Prince Charles has already visited the island in 2018, where he was appointed an honorary chief, and took part in a local ritual to confirm his new status.
Mr Huffman believes that based on the villagers' warm reception of Prince Charles – a shrine was built in his honour – the tradition of worshipping a British royal may continue.