Thomas Tresham was born into a wealthy and respected Northamptonshire family. His ancestors had come to Northamptonshire from Gloucestershire and became leading courtiers under the reign of Henry V and VI. The family acquired large estates in Northamptonshire including the manor houses of Rushton and Lyveden. Thomas inherited the estate from his grandfather in 1559, aged only 9. In 1575 Thomas Tresham was knighted at the Queen’s progress at Kenilworth.
In 1566, Tresham married into the Throckmorton family, a wealthy and respected Catholic family from Coughton Court in Warwickshire. The couple had nine children – three sons and six daughters of which four were married at generous expense to peers.