He yawned, distracted his cousins, and then knocked his sailor hat askew. At four years old, Prince William stole the show at the 1986 wedding of his uncle Prince Andrew to Sarah Ferguson.
Not hard to see where cheeky Prince Louis learned it from at the recent Jubilee. The then 60-year-old Queen even had to sprint after her grandson to stop him running behind their carriage.
Before he became the reserved, camera-shy, and seemingly at times, reluctant heir-in-waiting, pre-school Prince William was known for his strong will.
Even Her Majesty agreed with his mother, Princess Diana, he might benefit from nursery, so off he went - where he was reportedly known as ‘Basher Wills’ for a spell.
But it is perhaps that intrinsic determination and single-mindedness, now honed and matured as he approaches his 40th birthday on Tuesday, that we begin to see in William again as he emerges with a new public confidence and assurity in his ever closer role as one-day king.
The William of recent months is one we haven’t truly witnessed before. A commanding Duke who appears to stand on a level playing field with his father, sharing decision-making, who is reportedly outlining his preferred style of monarchy one day, with fewer staff, without the formalities of titles, bows and curtseys.
A Duke impassioned in his causes, and, one who a senior source claimed, felt assured enough this week to advise the Queen he would not attend the Garter Day service at Windsor if his uncle, Prince Andrew, did so publicly.
But if that comes as a surprise to us, it wouldn’t have done to his mother.
Princess Diana knew behind the shyness, there was a big personality and a born king, privately remarking: “The country is very lucky to have him.”
Former BBC Royal correspondent, Jennie Bond, recalls the day the Princess voiced it to her, when Prince William was around 12, having fireside chats with his grandmother about his future role, and starting to fret about his future.
She recalls: “Diana said William felt the burden of his destiny, his kingship, it weighed heavily on his shoulders.
“He was realising he wasn’t master of his own destiny like the other boys at school.
“But she said ‘I think William is alright’ - that was her phrase. ‘The country is very lucky to have him’.
“I think she was seeing a level of maturity and gradual acceptance of this strange destiny. Diana saw back then what we are seeing now.”
She may also have been referring to the fiercely protective little boy she described as “my wise little old man”, who watched his parents separate when he was ten, and who comforted her when she cried, passing tissues under the door.
He would later similarly guide his brother Harry after her tragic death, at the same time coping himself with “a pain like no other pain”, as he later described his grief.
He was, Royal biographer Ingrid Seward believes, always an emotionally intelligent boy, with traits of future leadership, adept at remembering everyone’s names, all the staff, even their pets.
Maybe the difficulties he experienced magnified that.
“He wanted to know everything about everyone, he was like his mother,” she says.
And he’s always had a firm sense of who he is, says Bond.
“He comes across as a lovely, gentle boy, but he has always known his own mind,” she says. “He has quite a temper too, and he will have his own way.
“He’s showing that now, by being forthright about what he wants.”
She adds: “We saw him wrestle with it a little bit in younger years, stories about him not really pulling his weight, shirking his responsibilities.
“Especially since Harry disappeared off the scene, William has visibly grown in stature and maturity and he now acts and seems like a future king. But a king who will do things his own way.”
A commemorative five pound coin will be minted with William’s portrait to mark his birthday. The Duke himself is apparently finding the milestone “daunting”.
But if he is not quite ready for middle-age, he seems increasingly ready for monarchy.
His grandmother’s mobility problems have propelled both Charles and his son centre stage.
They both attended the State Opening of Parliament in her place.
William was central at the Service of Thanksgiving at St Paul’s for the Jubilee, his face set intensely.
He spoke with command, authority and leadership at the Party at the Palace.
It is widely believed now he takes part in decision making with Prince Charles and the Queen.
Bond says: “The Queen and Charles have been very generous in the way they are treating William absolutely as an equal now.”
Seward agrees a larger space has definitely been curated for William. “He is being given the opportunity to shine,” she says.
But, she adds he is now “ready to occupy it”.
She points out William’s place is uniquely level with Charles’.
“Charles was always going to be an interim monarch,” she says. “It has been clearly managed so William is on a similar footing to his father.”
In earlier years rumours abounded of William’s reluctance to rule.
When he turned 21, he tried to address them, saying: “It’s not a question of wanting to be (king), it’s something I was born into and it’s my duty. Wanting is not the right word.”
Enthusiasm was muted.
But he added something telling.
“I like to be in control of my life because I have so many people around me – I can get pulled in one direction and then the other,” he said. “I could actually lose my identity.”
In the early years of his relationship with Kate his game plan seemed to be to fiercely guard that identity privately.
Now he appears to be making his identity overt.
His ill-judged Caribbean tour with Kate earlier this year seems to have been a turning point. Photos of them standing in a Land Rover, holding hands with children through wire fences, struck a bad note.
Breaking convention, William admitted afterwards the tour had “brought into even sharper focus questions about the past and the future”. Sources added he was “keen to have his own voice”.
Whispers swirled of a new way of ruling - a William way.
That will involve a closer awareness of PR, says Bond.
“Image is everything and I think William gets it.”
And William’s way also encompasses how he wants his family to live.
The planned move of his brood to a relatively modest four-bed cottage in the Windsor estate makes him righthand man to the Queen.
It also gives his family their final years of relative normalcy.
And by his side, at every step, is Kate.
It is widely believed their happy marriage is a key ingredient in this assured William.
“His strength is very tied up with the fact he has a happy marriage,” says Bond.
“Apparently it’s quite a sparky relationship. They will have shouting matches if they don’t agree. She is an equal partner in a huge sense.”
Finding himself as a father, a husband and an heir, seems to have bloomed in parallel for the Prince at 40.
“He’s thought, ‘this is my life, it’s not a bad life, and I’m going to make my mark’,” says Bond.
