Samuel Gilfillan McLaren was born on 17 September 1840 at Gask, Perthshire, Scotland. The son of Peter McLaren who was the head gardener of the Gask estate and elder of the church. A student with great academic promise, McLaren wanted to become a minister but the ambition remained dormant because he was reluctant to put his parents to the expence. Instead, at the age of sixteen he asked his father to article him to a legal and banking firm. Subsequently as McLaren gained a solid knowledge of the law during the day, he attended night school, studying mathematics and modern languages. After four years he joined a legal firm in Edinburgh , Tods, Murray & Jamieson where he was soon promoted to law clerk.

In 1870 Samuel McLaren consolidated his reputation in the legal fraternity when his firm sent him to the United States to work on the extraordinary case of the missing earl of Aberdeen. McLaren was assigned to establish the earl's brother as heir by proving that a man by the name of George Osborne who had been drowned in a storm at sea while serving as first mate on a ship bound for Melbourne, was indeed the Earl of Aberdeen. This absorbing case incited great public interest and McLaren successfully presented the petitioner's case in the House of Lords.

Now financially independent and still devoted to the idea of becoming a minister, McLaren turned his back on the law and entered the University of Edinburgh where he graduated M.A. in 1884. Then followed three years study in divinity at the Theological College and postgraduate work at Leipzig and Heidelberg. After McLaren was ordained, he married Marjorie Millar Bruce and was sent as a missionary to Japan, becoming Professor of History and Biblical Literature at the Presbyterian Union Theological Seminary, Tokyo. The conditions in Japan did not suit McLaren and after eight years,he was compelled to leave due to "lung toubles" and return to Scotland.

The homecoming proved brief and the McLaren family (now encompassing four children), migrated again in 1886, this time to Melbourne. Despite Samuel McLaren's "shattered health" and despondence regarding his employment prospects, he was inducted in the Coburg Church and also served as chaplain at Pentridge gaol for two years. In 1889, Samuel was selected by the Presbyterian Assembley to succeed Dr Andrew Harper as principal of the Presbyterian Ladies' College.