Born in Bernain, near Dunkeld in Scotland, Macpherson completed an apprenticeship as a drapers' assistant in Glasgow before moving to London in 1879.
He worked in a variety of retail positions and became a founder member of the National Union of Shop Assistants.
[1] In 1891, Macpherson joined the Social Democratic Federation and was a founder of its branch in Bow.
He was elected as general secretary of the soon-renamed National Amalgamated Union of Shop Assistants, Warehousemen and Clerks in 1894, holding the post until 1912.
[1] Margaret Bondfield was inspired to join the union after reading a letter from Macpherson in a newspaper.