In 1591 the Privy Council asked him, as Vice-Admiral, to adjudicate in the case of a Scottish ship belonging to an Edinburgh merchant Archibald Johnston wrecked on the coast of Norfolk.
He died in 1598.
- Robert Southwell, died 23 September 1586.
- Thomas Southwell (1598-1643) was his heir.
- Charles Southwell (2 February 1588 - 23 April 1588), buried at Reigate where the Howard family lived at Reigate Priory.
- Elizabeth Southwell (1584-1631), maid of honour to Queen Elizabeth from 1 January 1600 in the place of Margaret Radcliffe. She danced in the masque at the marriage of Henry Somerset, 1st Marquess of Worcester in June 1600. She was also maid of honour to Anne of Denmark, and third wife of Robert Dudley. She wrote an account of the death of Queen Elizabeth. She was buried in San Pancrazio, Florence where there was formerly a Latin inscription including her age, 37 years. Her portrait is drawn in an Italian armorial.
- Frances Southwell, gentlewoman of the privy chamber to Anne of Denmark, married Sir Edward Rodney of Rodney Stoke, Somerset, at Denmark House in 1614. The Earl of Rutland gave a wedding present of a gilt bowl and cover worth £21.
- Katherine Southwell, gentlewoman of the Privy Chamber to Anne of Denmark, who married Greville Verney, 7th Baron Willoughby de Broke in 1618.
Robert's half-sister, the daughter of Nazaret Newton, Elizabeth Southwell, was a Maid of Honour to Queen Elizabeth. She was a mistress of Robert Devereux, 2nd Earl of Essex and the mother of Walter Devereux. She married Sir Barentine Moleyns or Molyns of Clapcot.
- "SOUTHWELL, Sir Robert (1563-98), of Wood Rising, Norf. - History of Parliament Online". www.historyofparliamentonline.org.
- Calendar State Papers Scotland: 1589-1603, vol. 10 (Edinburgh, 1936), pp. 476, 517, 527.
- Mill Stephenson, 'A list of Monumental Brasses in Surrey', Surrey Archaeological Collections, vol. 32 (1919), p. 70.
- Michael Brennan, Noel Kinnamon, Margaret Hannay, The Letters of Rowland Whyte to Sir Robert Sidney (Philadelphia, 2013), pp. 377, 398.
- Michael Brennan, Noel Kinnamon, Margaret Hannay, The Letters of Rowland Whyte (Philadelphia, 2013), pp. 498, 501: Arthur Collins, Letters and Memorials of State, vol. 2 (London, 1746), p. 201: Roy Strong, The Cult of Elizabeth (London, 1977), pp. 28-43.
- Catherine Loomis, The Death of Elizabeth I: Remembering and Reconstructing the Virgin Queen (New York, 2010), pp. 83-5.
- John Temple Leader, Life of Sir Robert Dudley (Florence, 1895), pp. 9-10, 146.
- Norman Egbert McClure, Letters of John Chamberlain, vol. 1 (Philadelphia, 1939), p. 512.
- HMC Rutland vol. 4 (London, 1905), p. 500.
- Johanna Rickman, Love, Lust, and License in Early Modern England: Illicit Sex and the Nobility (Ashgate, 2008), pp. 30-32.
- Alan Davidson, 'MOLYNS, Michael (c.1601-at least 1662), of Clapcot', The History of Parliament: the House of Commons 1604-1629, ed. Andrew Thrush and John P. Ferris, 2010.