Dr William Drennan was the youngest son of Rev Thomas Drennan, minister of the First Presbyterian Church Belfast, and Anne Lennox. During this period Presbyterians were impacted by the Penal Codes, and as such many ‘sons of the manse’ attended university in Scotland. William Drennan studied arts in Glasgow (1772) and completed his medical studies in Edinburgh (1778).
On his return to Ireland he practised in Belfast, Newry and Dublin. During his time in Belfast he took an active interest in the Poor House, having been one of the original subscribers in 1774. On this day (9 March) 1782 Dr Drennan presented his paper on a scheme of public inoculation against small pox for the residents of the institution. This proposal was accepted and the children of the Poor House were inoculated with the permission of their parents. Dr Drennan was extremely passionate about vaccination and when his first child was born in Dublin, Dr Drennan inoculated him against the disease, much to the dislike of the child’s aunt.
