John Knyvett, (also spelt Knyvet and Knevitt), was born in Ashwellthorpe. He married Agnes, daughter of Sir John Harcourt of Stanton Harcourt, Oxfordshire and Ellenhall, Staffordshire, February 14, 1537 at Stanton Harcourt, Oxfordshire, England. She survived her husband and married second William Bowyer of Wimbledon, Keeper of the Records in the Tower. She died in 1579.

He was the eldest son and known as John Knyvett of Plumstead. He died February 17. 1561 in Ashwellthorpe.

National Archives (UK)
Reference: KNY 427 371 x 9
Agreement in support of marriage settlement, (1538).
Between John son of Edmund and Jane Knyvett and Agnes his wife daughter of Sir John Harcourt re manors of Horham, Thorpe Hall and 'Barnhold' (? East Bergholt) (co. Suffolk), and Thetford in the Isle of Ely (co. Cambridge).

Reference: KNY 409 371 x 8
Bargain and Sale, (1543)
From John Knyvett Esq. of Plumstead and wife Agnes to Robert Raghnold Esq. of their part of the manor of Illarys alias Newehall in East Bergholt, Stratford, Great Wenham, Capel, Butley, Holton, and Brantham, January 20.

Reference: KNY 432 371 x 9
Release
By Thomas Knyvett Esq. of Buckenham Castle of John Knyvett Esq. of Ashwellthorpe from covenants in an agreement, (June 20, 1550; October 6, 1551).

Reference: KNY 433 371 x 9
Bond from John Knyvett gent. of Buckenham to William Coke of London for payment of £7, (1552).

Reference: Phi/549 578 x 2
Bargain and Sale
Bargain and Sale by William Bowyer gent. and wife Agnes late wife of John Knyvett Esq. deceased to Thomas Knyvett Esq., son of said John of their life interest in the manors of Horham and Thorpehall in Suffolk and Thetford, Isle of Ely, of which Thomas had the reversion, (March 1, 1565).