He was the third, and youngest, son of Col. Sir William Smith, of Hill Hall, Essex, and the former Bridget Fleetwood.
[1] Smyth's paternal grandfather was George Smith, a London draper, who inherited the estate (which Thomas eventually inherited) of his brother, Sir Thomas Smith, the Secretary of State during the reigns of King Edward VI and Queen Elizabeth I, three-time Ambassador to France and Chancellor of the Order of the Garter.
[2] He was admitted to study law at Gray's Inn in 1619/20, and inherited the family estate of Hill Hall from his nephew, Edward Smith.
[5] The daughter of Francis Annesley, 1st Viscount Valentia and Dorothea Philipps (a daughter of Sir John Philipps, 1st Baronet of Picton Castle), she was a widow of both James Zouche and Sir John Lloyd, 1st Baronet.
[1] He died 5 May 1668 and was buried at Theydon Mount, near Epping, Essex, his monument bearing the 'Smyth' spelling used for the next several generations by his descendants.