He was born on 3 August 1764 the son of William Theed, a wig-maker in Wych Street in London and his wife Sarah Palmer.
[1] He was trained at the Royal Academy Schools in 1786 and began a career in oil painting: both portraits and classical subjects.
After a tour with other artists of Italy beginning in 1791 (where he spent 4 or 5 years in Rome and reportedly got married) he returned to England around 1796.
He worked as a modeller for Wedgwood from 1799 to 1804, and then for the gold and silversmiths Rundell and Bridge back in London from 1804 to 1817.
Theed, William I, in: A Biographical Dictionary of Sculptors in Britain, 1660–1851, Henry Moore Foundation