A notary by training, Letellier belonged to a prominent family that descended from Michel Letellier who, originally from Saint-Quentin, in the diocese of Noyon, migrated to New France around 1705 with his wife Marie Mélie. Their son, François Letellier de Saint-Just, born in Québec in 1709, became a soldier in Fouville's company and retired from the troops in October 1740, after marrying Marie-Françoise Pelletier in Québec on January 25, 1740. In February 1750, they had a son named Michel Tellier who, as a farmer, was a member of the House of Assembly of Lower Canada between 1800 and 1804. He and his wife Louise Moreau are the parents of François Letellier, notary, who married Marie-Sophie Casgrain, who are the parents of Luc Letellier de Saint-Just, who was a half-brother of Horace Bélanger.[1]
In 1876, Mackenzie advised the Governor General of Canada to appoint Letellier to the position of lieutenant-governor of Quebec. As lieutenant governor, he dismissed the government of ConservativeQuebec PremierCharles-Eugène Boucher de Boucherville on March 1, 1878, despite the fact that the government enjoyed a 20-seat majority in the Legislative Assembly and a two-to-one majority in the Legislative Council. Letellier justified the dismissal on charges that the government was acting incompetently and corruptly on the matter of railway legislation. He also argued that if the de Boucherville government had not made concessions to "rings" of interest within the legislature on the issue, it would have lost the legislature's support. De Boucherville called the move a "coup d'etat" and complained to the Governor General of Canada. Both houses of the legislature passed motions of censure against the lieutenant-governor.