Sir Robert Southwell, diplomat and government official was born at Kinsale, co. Cork. As well as being M.P. for Penrhyn and Lostwithiel, he was emissary to Portugal and ambassador to Brussels. The present lot appears to be an autograph version of the prime located at the Royal Society, London (see J.D. Stewart, Sir Godfrey Kneller, Oxford, 1983, p. 131, no. 704).