FitzGerald first entered parliament in 1808 as the member for
Ennis (succeeding his father), a seat he held until October 1812, when he was replaced by his father, and again between January 1813 and 1818. He was implicated in the scandal involving the
Duke of York and his mistress
Mary Anne Clarke, but after bringing valuable evidence of the case to the courts he was rewarded when he was appointed a Lord of the Irish Treasury and sworn of the
Irish Privy Council in 1810. In 1812 he was admitted to the
British Privy Council and made a
Lord of the Treasury in England,
Chancellor of the Irish Exchequer and First Lord of the Irish Treasury. He held the Irish offices until they were merged with the English treasury in 1816. In 1820 FitzGerald was returned to Parliament for
Clare, which constituency he represented until 1828. In 1820 he was appointed
Ambassador to Sweden. He tried to make the Swedish King,
Charles XIV John, repay the large sums of money given to him during the
Napoleonic Wars, but this was to no avail and he returned to Britain in 1823. He served as
Paymaster of the Forces under successively
Lord Liverpool,
George Canning and
Lord Goderich between 1826 and 1828. ==Personal life==