The eldest son of D'Arcy Wentworth, William Charles Wentworth (1793 - 1872) was born on Norfolk Island or on a ship bound for the island from Sydney. He attended school in England from 1803 and returned to Sydney in 1810. In 1813, in company with Gregory Blaxland and William Lawson, he made the first crossing of the Blue Mountains and opened the way for pastoral expansion on the western plains. He returned to England in 1816 to study law and was admitted to the Bar in 1822. From this period Wentworth emerged as a critc of the colonial administration. He supported the rights of emancipists and advocated the introduction of trial by jury and representative government.
On his return to Sydney in 1824, Wentworth and another barrister, Robert Wardell, established a newspaper, the Australian, in which they campaigned for political reform. Wentworth became the emancipists' acknowledged leader and was frequently involved in bitter disputes wit other factions of the community, notably the Macarthur family and the exclusivists. Governor Darling attempted unsuccessfully to silence the Australian by introducing licensing and stamp duty provisions, while the editors were several times prosecuted for seditious libel.
As vice-president of the Australian Patriotic Association, formed in 1835, Wentworth drafted a proposal for the colony's constitution. This fomed the basis of the Act eventually adopted in 1842. During this period, however, his policies became more conservative and aligned more with the wealthy pastoralists, of which he was now one, than with his former supporters.
In 1843 Wentworth was elected to the new Legislative Council. He was re-elected in 1851 and in 1853 headed a committee which drafted a new constitution. He went to England to see the Bill through the British Parliament in 1855 and returned to Australia only briefly, in 1861-62.