When he was 20, Mr Foster got the opportunity to experience the lifestyle for himself and settled in Rotorua to work for the Forest Research Institute. He first enrolled in a school certificate Maori course through a correspondence school while studying text by New Zealand missionary, linguist and translator Robert Maunsell. He later enrolled in classes held at Rotorua Boys' High School.
"I thought I was going to come to New Zealand, so obviously I needed to learn the language, it's the native language. The Maori language is a triumph in human intellect, because of the brilliance in its construction." he said.
"Because I was a telegraphist, I knew about codes and knew the percentage breakdown and frequency of certain words. It's very simple compared to other languages. For example, there's about five different words for the verb 'to talk' and in French there is the masculine and feminine nouns -- you haven't got any of that in Maori."
It was not long before Mr Foster was teaching evening classes himself at a nationally recognised level and in 1982 published his first textbook, He Whakamarama: A new course in Maori, which has since had 18 reprints and is accompanied with an audio CD.
He has released two other textbooks, which have had forewords by Sir Peter Tapsell and Sir Kingi Ihaka.
"The future of Maori is the responsibility of each and every one of us who can speak the language or have some knowledge of it. It is a duty to help anyone who is prepared to make a serious effort to learn.
"It was never intended by its originators to be esoteric and limited to a favoured minority," he said.