Successful WM businessman, born of humble parentage at Stokesley, N. Yorks. Beginning in a solicitor's office, he set up as a stockbroker in Halifax and then in Manchester, specializing in railway shares. He became Chairman of Star Life Assurance and of the South Eastern Railway and a director of other companies. On a visit to Banbury for a stonelaying, he found the Wykham Park estate on the market and set himself up there in 1865, becoming High Sheriff and then Deputy Lieutenant of Oxfordshire. He tithed his income and was a generous benefactor of the Banbury WM Circuit and of the NCHO. He provided the property in London which in 1890 became Mewburn House, the first residential house for Wesley Deaconesses and was named after him. His fourth daughter married Sir Robert Perks.
His son, also William Mewburn (1853-1932), born in Halifax on 7 April 1853, studied at University College, London and lived at Hawkwell Place, Pembury. He continued his father's business and philanthropic activities, including the lay treasurership of the Ministers' Children's Fund. When he retired in 1926, father and son had completed 61 years of continuous service in that office. He died at his Scottish home, Achnacharron, Argyllshire on14 May 1932. His son William Guy Mewburn married Priscilla Chubb.