William Pole-Tylney-Long-Wellesley, 4th Earl of Mornington a very dissipated life and lived for a time in Brussels to avoid his creditors. In his last years he lived on a small pension of ₤10 a week allowed by his cousin Arthur Wellesley, 2nd Duke of Wellington. From 1842 he was styled Viscount Wellesley, and succeeded his father as Earl of Mornington in 1845. He died in lodgings in Thayer Street, Manchester Square, London, on 1 July 1857, from heart disease. The obituary notice three days later in the "Morning Chronicle" claimed that he was "A spendthrift, a profligate, and a gambler in his youth, he became debauched
William Wellesley-Pole, 3rd Earl of Mornington 1835 Postmaster-General. From 1838 he held the honorary position of Captain of Deal Castle. On the death in 1842 of his elder brother Richard Wellesley, 1st Marquess Wellesley and 2nd Earl of Mornington, he succeeded as 3rd Earl of Mornington. In 1784 Lord Mornington married Katherine Elizabeth Forbes, daughter of Admiral John Forbes and granddaughter of the George Forbes, 3rd Earl of Granard, and of William Capell, 3rd Earl of Essex. They had the following progeny, one son and three daughters: He died on 22 February 1845. William Wellesley-Pole, 3rd Earl of Mornington William Wellesley-Pole, 3rd Earl of Mornington (20