He was the grandson of Henry VIII's chief minister, Thomas Cromwell, 1st earl of Essex, nephew of the Protector Somerset and first cousin of Edward VI.

[2] Shortly after the baptism, his parents left for Lewes in Sussex to the former Cluniac Priory of St. Pancras, recently acquired by his grandfather, where they remained from March 1538 until early 1539, when they took up residence in Leeds Castle, Kent.

A minor at his father's premature death from sweating sickness on 4 July 1551,[3][4] he was first summoned to Parliament in 1563.

[3] His stepfather later married, before 30 September 1568, Winifred, widow of Sir Richard Sackville, and daughter of John Brydges, a former Lord Mayor of London.

[11] His siblings included brother Thomas Cromwell and half-brother Sir Henry Ughtred, and his brother-in-law was William Paulet, later 3rd Marquess of Winchester.