Rickhill was the eldest son of
Sir William Rickhill (died 1407), of Ifield and
Islingham in
Frindsbury and his wife Rose (died 1418). Rose was close to William and left him her personal property. He was the elder brother of
John Rickhill, MP (died 1432), Nicholas and Alice, who married
William Skrene,
Chief Baron of the Irish Exchequer. Nicholas married a wealthy widow, but at his death in 1432 was entangled in numerous lawsuits, which William had the task of fighting or setting. William Rickhill married, before February 1421, Katherine Coventry, daughter of William Coventry, a London merchant. They had one daughter, and Katherine died on 27 August 1433. Their daughter married Edward Lymsey and had a son John, who was his grandfather's heir. ==Career==