Why did the 5th Earl of Derby die?

The unexpected death of Ferdinando Stanley, 5th Earl of Derby, on April 16, 1594 was an event of major political importance in the later years of Queen Elizabeth I of England. When he had succeeded his father at the age of 38 he became head of one of the most influential families in the country. He also had a claim to the throne if Elizabeth died without naming a successor. Yet within seven months of entering into his inheritance, this previously fit man was suddenly taken ill and died a fortnight later. His death was so significant that the historian John Stow recorded his illness in great detail (figure 1).1 Stowʹs remarkable account is compatible with a sinister interpretation of the cause.