John Grace was the son of John Edward Grace, JP, and Rangimohia Herekiekie II, chieftainess daughter of Kingi Te Herekiekie and the last of the senior ariki tapairu line of Ngāti Tuwharetoa. He was educated at Tokaanu Primary School, Wanganui Technical College and Te Aute College. At the age of twenty-one, Grace began working as a survey cadet for the Lands Department in Auckland and two years later joined Māori Affairs. He became private secretary to Peter Fraser during his time as Prime Minister and served with the R.N.Z.A.F. in World War II during which he rose to the rank of Squadron leader. From 1950-57 he was private secretary to the Minister of Māori Affairs, F. B. Corbett and later became private secretary for Keith Holyoake when he was Prime Minister and for Walter Nash when he held the Māori Affairs portfolio in the 1950s. Grace held many positions in the National Party, and contested the Wanganui seat in 1963 and 1966. He received a Knighthood in 1968 and in 1970 was appointed as first New Zealand High Commissioner to Fiji when Fiji gained its independence. He owned a sheep station on the Parapara Road, was an kaumatua of Ngāti Tuwharetoa and spent most of his life studying Māori traditions and history. Grace received the following honours: KBE, MVO, EA. He died in Wanganui at the age of eighty.
- Te Ao Hou 63 (1968): 38-39.
- Tu Tangata 26 (1985): 45
- Tuwharetoa: The History of the Māori people of the Taupo district. Wellington, N.Z.: Reed, 1959, 2nd ed. 1966, 1970. Excerpt in Te Karanga: Canterbury Māori Studies Association 12 (1985): 21-23.
- "Knighthood Conferred." In "People and Places." Te Ao Hou 63 (1968): 36-39.
- Duval, Terry. Te Karanga: Canterbury Māori Studies Association 1.2 (1985): 21-23.
- Duval provides a poroporoaki in Māori for Sir John Te H. Grace, which is followed by a brief biographical note and an excerpt from Grace’s book Tuwharetoa: A History of the Māori people of the Taupo District.
- "Sir John Grace dies aged 80." Wanganui Chronicle. No details. Rpt. in Tu Tangata 26 (1985): 45.
- Taylor, C. R. H. A Bibliography of Publications on the New Zealand Māori and the Moriori of the Chatham Islands. Oxford: At the Clarendon Press, Oxford UP, 1972. 87.
- Orbell, Margaret. Te Ao Hou 55 (1966): 62-63.
- Te Hau, M. Journal of the Polynesian Society 70 (1961): 379-380.