Graduated in medicine from Glasgow University 1839. Settled in Dublin that year and began to contribute to the newspapers, while practising medicine. Became joint proprietor of the Freeman's Journal and political editor in 1841. He supported the Repeal movement led by O'Connell; in 1843 he was sentenced to nine months' imprisonment for conspiracy, but the sentence was reversed.

In 1850 he became sole owner of the Freeman's Journal and increased its circulation. Elected to Dublin City Council 1852 and promoted the Vartry water supply scheme against strong opposition; knighted in 1863 when the scheme was inaugurated. MP for Kilkenny 1865-75. In Parliament he advocated disestablishment of the Church of Ireland, reform of the land laws, and free denominational education.

Through his paper he instituted a commission on disestablishment and in 1868 published its report, The Church Establishment in Ireland. A testimonial of £3,500 was presented to him in recognition of his work in this cause. Elected Lord Mayor of Dublin 1868 but declined office. Died Bath, 9 April 1875.