The son of Robert Southwell, an English diplomat in Ireland, Sir Robert Southwell was an MP, a Fellow of the Royal Society, and also a diplomat. He took his BA at Queen's College, Oxford in 1655, entered Lincoln's Inn in 1654, and was knighted in 1665, the year in which he went to Portugal as an English envoy. In 1677 he succeeded his father in a diplomatic post in Ireland, and in 1690 he became Principal Secretary of State for Ireland. He was President of the Royal Society from 1690 to 1695.
From The Continuum Encyclopedia of British Philosophy in Oxford Reference.