One of the earliest known autopsy reports will go on display in a exhibition this autumn. The Lost Prince: The Life and Death of Henry Stuart at the National Portrait Gallery will look at the extraordinary, albeit short, life of the eldest son of James I of England and VI of Scotland. Widely seen as an ideal prince, Henry would have become Henry IX had he lived. 

The autopsy was performed to disprove rumours that the 18-year-old prince had been poisoned. It will be shown alongside the remains of Henry's funeral effigy, from the collection of Westminster Abbey, but not seen in public for nearly 200 years.  

The prince might be described as the Princess Diana of his day. At his funeral, which was considerably bigger than that of Elizabeth I nine years earlier, one contemporary recorded the sight of the people lining the streets of London: "There was to bee seene an innumerable multitude of all sorts of ages and degrees of men, women and children...some weeping, crying, howling, wringing their hands, others halfe dead, sounding, sighing inwardly, others holding up their hands, passionately bewayling so great a losse, with Rivers, nay with Ocean of tears."

The exhibition will also feature some of the most important works of art produced in the Jacobean period, including portraits by Hans Holbein, Nicholas Hilliard, Isaac Oliver and Robert Peake, masque designs by Inigo Jones and a rarely seen manuscript by Ben Jonson in his own hand. 

• The Lost Prince: The Life and Death of Henry Stuart opens on 18 October at the National Portrait Gallery