At age seven, he entered the Royal Conservatory of Liège, and studied under Désiré Heynberg, Rodolphe Massart and Jacques Dupuis (1830-1870).
[2] In 1873, he became concertmaster of the private orchestra (52 players) of Baron Paul von Dervies, a Russian banker and railroad magnate, who, in 1870, had built the Castello di Trevano as a temple to music, in the vicinity of Canobbio, by Lugano, Switzerland.
After von Dervies lost his mind and disappeared, Thomson left Lugano in 1877, but not before he had married a local noblewoman, Luisa Riva.
[3] In 1879, he played in a Berlin orchestra, and in 1882 was appointed violin professor at his alma mater, the Liège Conservatory.
His notable students included: Hugo Alfvén, Oskar Back, Aylmer Buesst, Max Donner, Demetrius Dounis, Edwin Grasse, Johan Halvorsen, Guillermo Uribe Holguín, Paul Kochanski, Alma Moodie, Celia Torrá,[8] and Haydn Wood.