Born in Camberwell, London, Brotherton completed an apprenticeship as a sheet metal worker.
He joined the National Union of Sheet Metal Workers and Braziers in the final year of his apprenticeship, the earliest point at which he was eligible to do so.
[3][4] During World War II, he served on several government committees,[4] and in 1941 he was elected as the union's Assistant General Secretary.
[4] He also served as President of the Confederation of Shipbuilding and Engineering Unions from 1948 until 1958,[4][6] served on the Railway Shopmen's National Council, Engineering Advisory Council, and chaired the Gas Industry Negotiating Committee for Craftsmen.
[4] In the 1949 New Year Honours, Brotherton was made a Commander of the Order of the British Empire.