When the Queen left hospital after a brief stay earlier this month, she reputedly told her doctors not to “make a fuss’ – entirely in keeping with what we know about her stoical character.

But our monarchs have never been particularly docile patients. The doctors who look after them might well expect wealth, knighthoods and influence in return for their work. And yet their task isn’t always easy. If they do their job well, and their patient remains healthy, success is taken for granted. If the patient dies, heavy censure will inevitably follow.

No one knew this better than Sir Richard Croft. In 1817, when he was summoned to attend the lying-in of Princess Charlotte, 21-years old and second in line to the throne, he must have thought he’d ascended to the pinnacle of his profession.

But during the course of a 48-hour labour, Croft shilly-shallied about using the forceps to pull the baby out. Valuable time was lost, the child died, and a few hours later, so did the mother.

At a stroke, two generations of the royal family were wiped out. Princess Charlotte, the only legitimate daughter of the hated George IV, had been by far its most popular member. Croft was heavily blamed for failing to save her, and he took the criticism to heart. Just over a year later, he shot himself.

Part of the challenge facing a royal doctor is the notion that royal patients aren’t supposed to get ill at all. If you consider a pre-modern monarch such as Henry VIII, who still had immense personal authority, there was a significant overlap between his health, and that of England.

This has become clear to me in the filming of my new BBC Two series, Fit To Rule?, which explores how the physical and mental health of our monarchs has shaped the history of the nation. Henry VIII was only the second member of the Tudor dynasty. With the benefit of hindsight, its success seems inevitable, but at the time the succession was very precarious. If Henry had died before producing an heir, the consequences were potentially terrifying. A return to the Wars of the Roses? Invasion by France? No wonder that doctors, courtiers, ambassadors and spies alike all wanted reassurance that the king was in good health.

To this end, the king was kept under constant surveillance. Whenever he went “to make water”, he was accompanied. Notoriously, his top servant was the Groom of the Stool, whose job was to attend the king upon the close-stool, the padded seat-less rest placed over the chamber pot. Afterwards, the pot’s contents would be handed to the medical staff for analysis. In short, the king’s body, and his most private moments, were not his own.

Despite – or perhaps because of – all the eyes trained upon them, kings and queens would make great efforts to disguise any ill health. It was bad for business. One of George II’s courtiers wrote that he had known the king “get out of his bed, choking with a sore throat, and in a high fever, only to dress and have a levee, and in five minutes undress and return to his bed”. If news of his sickness leaked out, it would “disquiet the minds of his subjects, hurt public credit, and diminish the regard and duty which they owe him”.

Another difficulty facing royal doctors was not being allowed to tell the truth. In Henry VIII’s reign, to “predict the king’s death” was treason, a crime punishable by death. What, then, was a doctor to say, if he thought there was something seriously wrong?

One also suspects that kings and queens don’t make the easiest of patients. Henry VIII and George IV shared a common waist measurement of 54 inches. By a strange coincidence, that’s also the circumference of a pair of Queen Victoria’s under-drawers from later on in life (though these were worn bunched around the waist). All three of these monarchs had difficulty in restraining their appetites, and their doctors found pleas for moderation ignored.

Ironically, prominent people often experience poor medical care, because the stakes are high, their doctors are nervous, and no one wants to deliver bad news. An exception to this rule was Dr Francis Willis, the physician who finally had some success in treating George III during his episodes of so-called madness. Only this “mad doctor”, an experienced asylum-keeper from Lincolnshire, seemed to have the strength of character to persuade the king to both exercise and rest. It did not endear Willis to the coterie of existing royal doctors, who’d all failed to bring about any improvement.

Queen Victoria, in particular, suffered terribly from having no one who could say “no” to her after the loss of her beloved husband Albert in 1861. As she herself put it, he had been the only person who called her not “Your Majesty”, but “Victoria”.

Of course she mourned him deeply, but as the years went by and his death receded into the past, nobody dared tell her that she was starting to wallow in her grief. A succession of tame physicians wrote a series of royal sick notes excusing the queen from public appearances for nearly a decade, and, in the process, doing grave damage to the royal image. In order to be believed, royalty has to constantly be seen.

Royal doctors inevitably get drawn into matters of presentation, and what we might today call spin. The best-known example of this was the involvement of Lord Dawson, the king’s doctor, at the death of George V in 1936, in an act amounting to euthanasia. Dawson administered a dose of morphine to speed the king’s passing, so that the announcement would reach “the morning papers rather than the less appropriate evening journals”.

Centuries earlier, we also see Henry VIII’s physician Dr William Butts performing a similar role in putting the most positive spin possible on the king’s health. Butts, only the second physician to receive a knighthood, had enormous authority at court. In 1540, Henry was keen to have his marriage to wife number four, Anne of Cleves, annulled. To achieve this end, Dr Butts testified to an enquiry at the House of Lords that the king had not had intercourse with her.

However, lest damaging rumours begin to circulate that the aging king was now impotent, Dr Butts was also required to reveal that the king was well “able to do the act with others but not with her”, and that he still experienced “pollutiones nocturnes”.

The pressure, the politics and the potential risks to reputation all make being a royal doctor much less attractive than you might at first think.

Dr Lucy Worsley is chief curator at Historic Royal Palaces. Her new series, Fit to Rule?, will begin on BBC Two next month