McArthur, Sir William (1809–87), politician, was born on 6 July 1809 in Malin, Co. Donegal, the fifth child of the five sons and two daughters of John McArthur, Wesleyan minister, and his wife, Sarah (née Finlay), of Malin. He was educated at private schools in Stranorlar, Co. Donegal, where Isaac Butt (qv) was reputedly a fellow pupil, and Ardstraw, Co. Tyrone. In July 1821 he was apprenticed to Hugh Copeland, a woollen draper in Enniskillen, and four years later, having completed his apprenticeship, moved to Lurgan, where he worked as an accounts clerk for William Johnstone, a manufacturing tobacconist and spirit merchant. Around this time he published verse under the penname ‘Gulielmus’ in the Impartial Reporter, an Enniskillen paper. McArthur spent a year in Dublin working as an assistant to Thomas Steele, a woollen draper in Wellington Quay, before moving in 1831 to Derry, where he established a woollen drapery business with Joseph Cather, a businessman who dealt in leather. The partnership was dissolved in 1835 and McArthur continued independently, becoming a leading figure in local business and methodist circles.
McArthur's political career began in 1841, when he was elected as a moderate conservative to Derry's town council (he was returned also in 1842, 1848, and 1851). In 1852 he served as member and honorary secretary of the Londonderry Improvement Association, which successfully campaigned for – among other things – a new stone bridge for the city. He collaborated with his brother in an export business based in Sydney, which proved so successful (particularly after the 1851 gold rush) that they entered into partnership and opened branches throughout Australia, as well as an office in London (1854). McArthur was soon spending so much of his time in England on business that in 1857 he transferred his firm to 43 Moorgate Street, London, and established a private home in Brixton.
McArthur's political outlook modified somewhat in the 1850s, largely in reponse to his rather bizarre perception of the policies of Lord Derby (qv) as anti-protestant. In July 1865 he stood unsucessfully for Pontefract as a liberal. Motivated by his staunch Wesleyan methodist belief, he increasingly focused his energies on his public political career and a wide range of philanthropic projects. He was prominent in the Wesleyan Connexion, to which he subscribed generously, serving on many of its committees and as director of the Wesleyan Methodist Newspaper Company (established in 1862). In 1866 he visited Ireland to lay the foundation stone of Methodist College, Belfast, and in the same year participated in an American mission. He was a fervent evangelist who was committed to furthering missionary work in the British empire, becoming involved in the British and Foreign Bible Society, the Evangelical Alliance, the Aborigines Protection Society, the Hospital Bible Sunday Committee, and the London City Mission.
In November 1868 McArthur was returned for Lambeth, a constituency he represented until 1885. His religious beliefs generally determined his political agenda, to which end he strongly supported the movement to annex Fiji (strenuously opposed by Gladstone). Irish affairs and education were also abiding concerns; he spoke in support of the Maynooth grant (May 1869) and served on the Wesleyan committee advising on the Education Act (1869–70). A pre-eminent figure in London, he was elected sheriff of London and Middlesex (June 1867), city alderman (1872), master of the Spectacle Maker's Company (1875), and lord mayor (1880). In the public eye, McArthur was inseparable from his religion; during his mayoralty it was remarked that Mansion House should be renamed the ‘city tabernacle’. He was influential in business circles and was a founder member of the London chamber of commerce (1881). His public service was recognised in the award of a KCMG (1882).
In 1881 McArthur moved to 79 Holland Park, Kensington, and four years later his parliamentary career came to an end when he stood unsucessfully for West Newington. While travelling on an underground train to a business meeting he suffered heart failure and died 16 November 1887 near Paddington. He was buried in Norwood cemetery, London. His substantial bequests to methodist charities included a large sum to Methodist College, Belfast, for the foundation of a girls’ hall of residence.
McArthur married Marianne (d. 1889), the only child of Archibald McElwaine, a methodist businessman in Coleraine, on 5 September 1843; they had no children. A portrait is in the Guildhall Library and Art Gallery, London; letters to Gladstone are in the British Library, London.