The Tudors retained only a precarious grip on the crown of England, founded on a title that was both tenuous and legally flimsy.
This left them preoccupied by two major obsessions: the necessity for a crop of lusty male heirs to continue their bloodline, and the elimination of threats from those who had strong, if not superior, claims to the throne than them.
None was cursed more by this rampant insecurity than Henry VIII.
The king embodied not only the power and imperial majesty of the monarchy, but also England's stature and military might.
His health always had huge political consequences at home and overseas - hence his unbridled hypochondria.
Henry's last six years saw him embark on two marriages, brutal wars against Scotland and France and the devastating collapse of England's economy.
Terror stalked his court, as factions plotted in the shadows behind the throne to snatch ascendancy in religion and political influence.
Drawing on the latest historical and medical research, Robert Hutchinson reveals the extent to which the king also grappled with accelerating geriatric decay, made more acute by medical conditions that were not only painful but transformed the monarch into a 28-stone psychotic monster, suspicious of everyone around him, including those most dear to him.