|William Pitt by W.H. Brown|
In November 1957, R. Guest Gornall published an article in The Practitioner, Vol. 179 on the health of William Pitt the younger. Specifically, Gornall wanted to know what caused Pitt's early death at forty-six when both of his parents lived to old age.
Was it hastened by the interminable all-night sittings in the House of Commons? Was it the inevitable consequence of the long-term stress associated with running a country for seventeen years? Did it result from the crushing disappointments of several failed coalitions, and the ill-fated Battle of Austerlitz? Perhaps a combination of all of the above? Or, could it have been something entirely different?
Whatever the actual cause of Pitt's death, we must be careful not to examine Pitt's medical conditions from a purely modern lens. With Pitt’s case in particular, recorded details of his health are vague. Physicians left little or no records, and biographers - lacking firm evidence - have focused on his political life instead. Indeed, Pitt himself persistently made light of his health to allay his mother’s fears. There could also have been a political motivation to downplay his health. He wanted others to believe he was in control, and could handle the pressures of office. 
Gornall believed that “the irregular hours of unfettered bachelordom"did not help Pitt's health.  It is questionable whether Pitt's marital state impinged upon his well-being, but it may have helped him to have a wife around to regulate his hours.
So what were the potential causes of Pitt’s death?
Different explanations put forward have included a pyloric lesion (a recurring stomach ulcer), infective endocarditis (a heart infection), and Typhus fever.
William was not without his fair share of physicians. Dr. Anthony Addington was his childhood doctor until the age of fourteen, and Dr. Robert Glynn attended him at Pembroke Hall during his illness in the autumn of 1773. Dr. Hunter removed a cyst from Pitt's cheek in September 1786, and Sir Walter Farquhar was Pitt's personal physician from the mid-1790s up until his death. Lastly, Dr. Mathew Baillie (a nephew of the Hunters) and Henry Revell Reynolds examined Pitt at Putney in January 1806.
From the 1950s medical opinion R. Guest Gornall consulted, he concluded that “a recurring upper gastro-intestinal lesion," accompanied by “cardio-respiratory changes hinted at in the final medical bulletins” (The Gentleman’s Magazine, 1806) caused Pitt's early demise. 
This post is primarily about Gornall's opinion, and obviously medical science has improved since that time. Nevertheless, at this distance, we cannot be certain what caused Pitt’s death. In line with Lord Liverpool's opinion, I doubt whether retirement from public office would have greatly protracted Pitt's life.
1. R. Guest Gornall (1927) 'The Prime Minister's Health: William Pitt the Younger,' The Practitioner, Vol. 179, p. 4
2. Ibid, p. 5.
3. Ibid, p. 7.