In other words, James is warning the prince that actions speak louder than words. If the people observe a prince’s behaviour to be light-weight ‘or dissolute’, they might deduce that he will be a light-weight sovereign. For a royal born in the late 1500s, pleading respect for your privacy was not an option. The price of such vast privilege was a weighty awareness of duty. From the moment of his birth, Henry Stuart was a king in waiting.

In this picture, he is two years old – his high chair is his throne. His rattle is his orb. His little bunch of cherries are his sceptre. That wonderful domed, red velvet hat embroidered with real gold thread, is a soft version of a crown. Every single thing about this picture breathes royalty. The hair is blonde, downy, baby hair. But that steady gaze is mature and watchful. I don’t know how realistic this is. But if this ‘outward’ image is intended to show Henry’s ‘inward virtuous disposition’, then the country can rest easy. It’s a good start.

For me, King James’s words haunt the debates about Prince William and his family and their role ‘set on a stage’ as important royals. Arguments about what it meant to be royal and how to conduct yourself raged then, as they do now. Shakespeare is full of arguments about kingship, about ‘the head that bears the Crown.’ What did the prince owe his private self and what did he owe ‘the Crown’, that office you were called to bear?

I wonder, who is more regal – this small boy painted over 400 years ago – or the young royals today?  Of course, ‘the past is another country. They do things differently there.’ Still, there are residual similarities – we still discuss the nature and function of royalty. It’s a difficult role, but there are a million worse jobs.

They were not naive, these royals who lived through one of the supreme ages of monarchy. Prince Henry, and his father James VI & I, and Henry’s younger brother, the future Charles I, were all thought to be secretive. You can hardly blame them. A bit of secrecy and withholding of information allowed them to guard themselves, when their every move and breath was commented on and reported back to courts across Europe.

We know Prince Henry Stuart valued his privacy. He also became more secretive as he began to disagree with his father on important matters like foreign policy. Henry’s motto was, ‘Glory is the torch of the upright mind.’ It meant, winning eternal fame by heroism on the battlefield. King James chose ‘Blessed are the peacemakers’ for his motto. You can see where that difference could lead, when the question of whether to take up arms against an enemy, or appease them, arose.

Once you did have Henry’s confidence, however, he relaxed and opened up. He loved banter and jokes, music and dancing, and staging lavish court spectacles to get his political message across.

A highly educated Renaissance prince, he was sports mad. He spent hours every day on swordsmanship, learning how to handle pistols and cannon, on hunting, and, above all, on mastering manège, or horsemanship.

The early 1600s are a period of military innovation. Cavalry and infantry regiments will replace knights charging in full armour. Henry and his friends loved to practice for hours every day, teaching their horses to turn on a penny and stay calm under fire. I see him like our own sons, in the way he revelled in his physical fitness. And pushed his body to its limits. And thought himself indestructible. There is a bit of Icarus in so many young men.

Henry patronised ‘Projectors’ – what we would call ‘entrepreneurs’ and set about a major renovation and upgrade of the assets and estates he inherited as Prince of Wales – Wales, Cornwall, and so on. Princes were expected, slightly unrealistically, to ‘live of their own.’ They had to support themselves, not wait for state handouts. The Civil List had not yet begun. It makes you wonder what effect having to be self-sufficient would have on our royals? It is a dignifying thing to work to support yourself and your family.

Henry Stuart was a devout puritan minded Protestant, with a youth’s black and white morality. He made himself ‘Protector of Virginia’ and was the driving force behind the birth of British America. In 1607, he backed the expedition that planted the British race in American soil permanently, for the first time – 13 years before the Pilgrim Fathers set sail.

Henry enjoyed a loving relationship with his siblings and parents. Unlike the Tudors, the Stuarts are good family people. He was loyal. Loyal to a fault, in fact. Henry  would defend a man who was obviously guilty of corruption, just because the man had his trust. I hope Henry would have had the humility, and confidence to see, and own up to his mistakes – if he had lived.