Sir William Mather was born in Manchester in 1838. He became assistant manager at Mather & Platt in 1858, and was made partner in 1862 and took over running of the business in 1868, on the retirement of his uncle Colin Mather and co-founder William Wilkinson Platt. First elected as a Liberal MP in 1885, for the sourthern division of Salford. In 1892, Mather & Platt became a limited company and Sir William Mather was appointed as Chairman. He was knighted in 1902 and retired in 1916. He died at his home in the New Forest in 1920.

During his working life, Sir William Mather was noted for his concerns on the conditions and the welfare of workers. He undertook research on trips abroad, most notably to America in the late 1800s, and compiled notes for various publications and lectures on the subject. In 1873, he established the Salford Iron Works' Evening Science School and in 1893, he introduced an eight hour working day for his employees.