Born Edward Garth, he was the son of Joseph Garth and his wife Sarah (née Gee). On his mother's side he was a great-great-grandson of Sir Edward Turnor, who was Speaker of the House of Commons from 1661 to 1671.
On succeeding to the Turnour estates, including Shillinglee in West Sussex, in 1744, he assumed by Royal licence the surname of Turnour in lieu of Garth. In March 1761 he was raised to the Peerage of Ireland as Baron Winterton, of Gort in the County of Galway. In December of the same year Winterton was elected to the House of Commons for Bramber, a seat he held until 1769. He was further honoured when he was created Viscount Turnour, of Gort in the County of Galway, and Earl Winterton, in the County of Galway, in 1766, also in the Peerage of Ireland.
Lord Winterton died in August 1788 and was succeeded in the earldom by his son Edward.
He married Anne Archer (died 20 June 1775) on 13 March 1756, daughter of Thomas Archer, 1st Baron Archer, and Catharine Tipping. They had five children:
He then married Elizabeth Armstrong on 18 February 1778; they had one child:
|Parliament of Great Britain|
| Member of Parliament for Bramber
With: William Fitzherbert 1761-1762
George Venables-Vernon 1762-1768
Charles Lowndes 1768-1769
|Peerage of Ireland|
|New creation|| Earl Winterton
| Baron Winterton|