Johnston, William (1818–94), presbyterian minister and philanthropist, was born 2 January 1818 at his maternal grandfather's home, Crieve House, near Ballybay, Co. Monaghan, the eldest child of the Rev. John Johnston (qv) (d. 1862) of Cootehill, Co. Cavan, and Frances Johnston (née Jackson, d. 1838). His father, minister for Tullylish, Co. Down, was appointed moderator of the general assembly in 1858. Educated at a private school at Banbridge, Co. Down, and the Belfast Academy, as a teenager William expressed an interest in becoming a minister, after which he studied theology in Belfast (1837–8) and at the University of Edinburgh (1839). In Edinburgh his Free Church sympathies became more pronounced. He was licensed by the presbytery of Dromore (November 1840) and preached in vacancies at mission stations in Clonmel, Ardglass, and Loughbrickland, before being appointed to the Berry Street congregation in College Square, Belfast, in 1842, where he was ordained 17 May 1842. His life-long interest in the well-being of the Belfast poor dates from his time in Berry Street, where, serving a mainly working-class congregation, he became familiar with the problems faced by the city's industrial workforce. He was well known to the poor as an open-air preacher, through regular household visits, and for his work with the sick during the cholera epidemic of the late 1840s, when he was appointed to the board of health (1848). He contracted cholera himself in 1859 and was for a time seriously ill.
While he was recognised as an enthusiastic and capable minister, it was not until Johnston began his ministry in Townsend Street, Belfast (September 1847), that he made a name for himself in church circles. Following his move there he became increasingly interested in education and was closely involved in setting up day schools throughout the city – so much so that by the late 1870s he had nineteen national schools under his management. Well known in philanthropic circles, he was a committee and board member of numerous charities, among them the Deaf and Dumb Institution, the Hibernian Bible Society, the Hampton House and Frederick Street industrial schools, the Belfast Institution for the Employment of the Industrious Blind, the Society for the Prevention of Cruelty to Animals, the Consumptive Hospital, the Society for Providing Nurses for the Sick Poor, and the Royal Hospital, of which he was a life governor. Within the church he was recognised particularly for his work as founder of the Sabbath School Society (1862), the Society for the Orphans of Ministers and Missionaries (1872), the Fund for Aged and Infirm Ministers (1879), and the Presbyterian Orphan Society, which he helped establish in 1866 in response to Dr Wilberforce Arnold's article ‘Our fatherless’, which appeared in both the Evangelical Witness and Missionary Herald in November 1865. He served as honorary secretary to both the orphan and Sabbath school societies from their inception until 1893 and 1894 respectively. His work with orphans proved particularly effective and led to the establishment of the Training Home for Girls (1887). In this he was assisted by his wife Sarah Johnston (d. 1896), daughter of the Rev. James Porter, of Drumlee, Co. Down, whom he had married in March 1855. She was president of the Comrades’ Guild Society, through which women who had attended the training home maintained contact.
In 1864 the church sent Johnston to Canada to report on the condition of the presbyterian congregation there, which was then receiving aid from the Irish Colonial Mission. During his six-month stay in Canada he attended the synod of the Canadian presbyterian church. After his return he was elected moderator of the general assembly in 1872 and 1873, earning universal respect among his colleagues for his diplomacy in handling the controversy over orchestral music then raging in the church. He was an effective manager and fund-raiser; his own church in Townsend Street was rebuilt at a cost of £11,210 and re-opened in October 1878 free of debt. He played an active role in the Belfast presbytery's church extension committee, of which he was appointed convenor in 1881, and assisted in the building of several new churches in the city. An enthusiastic advocate of temperance and Sunday closing, Johnston was a member of the Clerical Temperance Association, for which he wrote tracts, and a secretary of the Belfast branch of the prohibitionist United Kingdom Alliance. He received an honorary doctorate in divinity from Princeton University in 1879. In failing health, he resigned his ministry in March 1892, and died 10 January 1894 at his home, Dunedin, Antrim Road, Belfast; he was buried in the city cemetery. His portrait, by Richard Hooke, and bust, by Bruce Joy, are in the Townsend Street church. Johnston's brother Henry Martyn Johnston (June 1876), a noted Belfast physician, was also a prominent philanthropist.