Battle of Bosworth Field
Buck was baptised on 1 October 1560 in Holy Trinity, Ely, Cambridgeshire. He was the eldest son and probably second of the four children of Elizabeth Nunn, "née" Petterill, of Brandon Ferry, Suffolk, and Robert Buck (d. 1580), a church official. His great-grandfather, Sir John Buck, was executed after supporting Richard III at the Battle of Bosworth Field.