John de Trelony was the son of William de Trelony. He married Joan, the daughter of Sir Reginald de Botrell. Sir Reginald was an associate of his father, who had confirmed the family's right to their estates.

Links to additional material:

• The Baronetage of England, or, The history of the English baronets, and such Baronets of Scotland as are of English Families, by Rev. William Betham, published 1801 [available as Google e-Book]
• The English Baronetage: Containing a Genealogical and Historical Account of All the English Barnonets Now Existing: Their Descents, Marriages and Issues, Volume 2, By Arthur Collins, published 1741 [available as Google e-Book]
• The visitations of Cornwall: comprising the Heralds' visitations of 1530, 1573 & 1620, John Lambrick Vivian›, College of Arms, published 1887 [available as Google e-Book]