Pulling faces, saluting the fly-past and his outfit, which was eerily similar to one donned by his uncle Prince Harry in 1989, all captured the attention of the press and public.
This large amount of interest in the youngest child of the Prince and Princess of Wales is almost certainly well intentioned: he is a sweet, exuberant child, who appears naturally inclined to show more of his personality than his poised older siblings, George (nine) and Charlotte (eight).
After the coronation on 6 May, television presenter Lorraine Kelly noted on her ITV talk show that, "Little Prince Louis, he's now, whether he likes it or not, he's now the family clown [...] he's going to have that around his neck for the rest of his life probably".
What impact did being in the public eye as a child have on Harry?
This assessment reflects Harry's own experience of growing up in the spotlight. In his memoir Spare — and his recent witness statement in his trial against MGN — the duke explored how the role he was cast in the press impacted him mentally.
"I'd been cast in my role in the Rolling Royal Melodrama. Long before I was old enough to drink a beer (legally) it became dogma. Harry? Yeah, he’s the naughty one. Naughty became the tide I swam against, the headwind I flew against, the daily expectation I could never hope to shake.
"I didn’t want to be naughty [...] but every sin, every misstep, every setback triggered the same tired label, and the same public condemnations, and thereby reinforced the conventional wisdom that I was innately naughty."
Counselling Directory member Georgina Sturmer, explains to Yahoo UK that this is something we all experience, but on a smaller scale.
"Think about the role that you played in your family growing up. Were you the naughty one, the clever one, the rebellious one, the clown, the quiet one, the ‘middle child’. Have you lived up to this expectation, or have you left it behind you?
"Now imagine that this reputation extends past your immediate family, into the eyes of the whole nation. This could leave us feeling trapped in an image or stereotype that we have no control over. We might feel that we need to live up to this image, to gain approval or affection from others. It doesn’t offer us space to learn and grow and develop. If our reputation precedes us, then every friendship or relationship begins with one person having preconceived ideas about the other."
The Wales children being in the spotlight is — as it was with Harry and William — to some extent unavoidable: they have been born into a public life, and a family the UK tries to sell as its national brand.
Sturmer points out the importance of the UN Convention on the Rights of the Child when it comes to the royal children, which "sets out the civil, political, economic, social, and cultural rights that all children everywhere are entitled to.
"This might sound like total overkill," she says, "but it offers helpful reminders of how children should be treated.
"It encourages us to think about their right to privacy, their right to express their views, and their right to be protected from exploitation."
'The stakes are much higher' for royal children
Sturmer also explains the impact that being in the public eye can have on a child's brain development — something that Kate may be aware of, given her early years sector campaigning.
"As our brains develop, we form our sense of identity and self-worth in response to our interactions with others. Looking back, we often remember the messages we received from caregivers, family, and friends. These messages help us to understand how to elicit praise, attention, and affection."
Sturmer outlines common themes that may sound familiar:
'Don’t speak until you are spoken to’
'Don’t make a fuss’
'Keep a stiff upper lip’
'Be a good girl’
'Boys don’t cry’
Imagine then, that you’re growing up under a media spotlight.
"The stakes become much higher. If you get something wrong, you’re not just risking disapproval or punishment," says Sturmer. "You’re risking the family reputation.
"This can lead to frustration, resentment, or anger. These feelings might manifest themselves in different ways. At one end of the spectrum, we might become rebellious. At the other end of the spectrum, we might become ‘people pleasers’, and lose our sense of our own needs."
With parents who are so passionate about raising awareness around mental health issues, it's likely the Wales children will have some measures put in place, to avoid any of them experiencing the struggles their uncle, Prince Harry, endured because of press intrusion, whilst preparing them for public life as adults.
Sturmer suggests that these measures could include limiting access to social media, boundaries and modelling behaviour.
"[Kate and William] should be clear to the children about measures that are taken to protect them," she explains. "This might include rules around photography and public appearances. If they have a good understanding of how their parents protected them, then they are perhaps less likely to look back with resentment."
Watch: How toxic is the Royal Family's relationship with the press?