In 1540, Smith went abroad, and, after studying in France and Italy and taking a degree in law at the University of Padua, he returned to Cambridge in 1542.
During the protectorate of Edward Seymour, 1st Duke of Somerset, he entered public life and was made the Secretary of State, and was sent on an important diplomatic mission to Brussels.
On the accession of Queen Mary I he lost all his offices, but in the reign of her sister, Elizabeth I, he was prominently employed in public affairs.
Ennobled as Lord Burghley, Cecil appointed Smith to the Privy Council, only a month before he was elected to Commons as a knight of the shire for Essex.
Smith, a prime mover behind the Conformity Bills, sought to restrain extremism and secure a subsidy from his fellow members.
He spoke on the Treason Bill on the floor of the house, and examined witnesses to the Catholic plot led by the Duke of Norfolk.
His outstanding work elevated him to the higher ministerial echelons: in 1572 he was appointed Chancellor of the Order of the Garter and in July, principal secretary.
[citation needed] Unfortunately for Smith, the booklet he printed to advertise his new lands was read by the Clandeboye O'Neill chief, Sir Brian MacPhelim, who just a few years earlier had been knighted by Elizabeth.
Then launching a wave of attacks on these early English settlers when they arrived, the O'Neills scorched the land Smith was to develop, burning abbeys, monasteries and churches, and leaving Clandeboye "totally waste and void of inhabitants".
[14] Sir Thomas Smith's book De Republica Anglorum: the Maner of Gouernement or Policie of the Realme of England,[15] written between 1562 and 1565, was first published in 1583.
Smith also authored De recta & emendata lingvæ Anglicæ scriptione, dialogus (Correct and Improved English Writing, a Dialogue, 1568).