He was the son of William Thornton of Yorkshire, Member of Parliament for York, 1747–54 and 1758–61; his mother Mary was the daughter of John Myster of Epsom.
[4] In 1794, a dispute arose between Thornton and some of the officers of the militia unit under his command, while stationed at Roborough Camp in Devon.
[1] Letters to the Earl of Darlington, giving an account of Thornton's second French trip, were written up by a clergyman named Martyn, and appeared in 1806 under the title of A Sporting Tour in France.
He owned a number of such weapons and the above portrait by Philip Reinagle and Sawrey Gilpin shows him armed with one of them,[9] One of Thornton's volley guns—an extremely unusual, 14-barrel rifle—survives and is part of the armouries collection of Le Grand Curtius museum in Liege, Belgium.
[10] The weapon is inscribed in gold damascene with words "Perdition to Conspirators" and "With this alone I'll defend Robro Camp 1795", a reference to the events around five years earlier that led to the loss of Thornton's military command.
[2] Alicia became famous in her own right as the jockey who rode in two challenges of 1804–5,[5] while Thornton was made notorious for the large bets on these races.
Alicia raced her brother-in-law, Captain Flint, over four miles at Knavesmire, riding Thornton's horse Vinigrillo.
At the following year's York meeting, Alicia rode against Frank Buckle, and won; but Thornton was horsewhipped by Flint, after refusing to honour the bet of 1000 guineas he had made on the 1804 race.
[2][15] Thornton married at Lambeth, in 1806, Eliza Cawston of Mundon, Essex, by whom he had a son, William Thomas, born in London in 1807.
By a will executed in London in 1818 he bequeathed almost all his property to Thornvillia Diana Thornton, his illegitimate daughter, then aged 17, by Priscilla Duins.
The will was disputed by his widow on behalf of her son, and both the prerogative court and French tribunals pronounced against its validity.