From an old St Ouen family, Frank Le Maistre spoke and wrote his native language all his life. He was editor of the quarterly bulletin of L’Assembliée d'Jèrriais from 1952 to 1977.
After leaving school he worked in a lawyer’s office and then for the Department of Agriculture at the States Farm. This work took him throughout Jersey, giving him the opportunity to speak to and question many old Jèrriais speakers for more than four decades, a period during which he collected hundreds of Jèrriais words and phrases from all the parishes and produced numerous literary works and histories.
During the ‘thirties and the Occupation he produced articles for the Chroniques de Jersey under the pen name Marie la Pie.
The deep knowledge of linguistics which he acquired permitted him to compose his remarkable Dictionnaire Jersiais-Français (published 1966) and collaborate on the English-Jersey Language Vocabulary (1972). He was awarded the Prix littéraire du Cotentin in 1967, and the Order of the British Empire in 1976. He also received a fellowship of the Royal Academy of Uppsala, titles of Commandeur dans l'Ordre des Arts et des Lettres, Membre de l'Académie des Arts, Sciences et Belles Lettres de caen, Medaille de Bronze from the Centre Nationale de la Recherche Scientifique, and Officier dans l'Ordre des Palmes Academiques. He received an honorary doctorate from the University of Caen.