Herbert Samuel Holt was born in Dublin, Ireland in 1856 and studied civil engineering there. When he arrived in Canada in 1875, he supervised the installation of the railway tracks from 1883 to 1889. In 1901, he founded the Montreal Light, Heat and Power company, which was created from the merger of Royal Electric and its subsidiaries (Montreal and St. Lawrence Light, Heat and Power and Chambly Manufacturing) as well as from Montreal Gas Co.
Two years later, he noted that the Lachine Rapids Hydraulic and Land Co. had a 25-year exclusive contract with the major Shawinigan Water and Power corporation. Wanting to acquire that firm, he succeeded in convincing seasoned businessmen, including Rodolphe Forget, to work with him to acquire the Lachine Rapids Hydraulic and Land Co., which would give Montreal Light, Heat and Power the monopoly over the distribution of electricity on the island of Montréal. Herbert Samuel Holt was a member of a number of Boards of Directors of various corporations in Montréal, and particularly, the Royal Bank of Canada, where he served as Chairman (1908-1934).