They got the giggles. Of course they did. You would, wouldn't you, with all those eyes on you - the 600 or so guests behind them, a not insignificant number in itself, without even beginning to count the eyeballs watching via the many cameras dotted around St George's Chapel.
And giggling, as we all know from school assemblies and parental lectures, is more often than not a nervous reaction, a way of breaking the ice and acknowledging the ridiculous in the sublime or serious.
The often amused looks on the faces of the new Duke and Duchess of Sussex suggested that this is a couple who would have been just as happy eloping and celebrating alone in a cabin in the woods.
Tradition demanded something different of them, of course - though tradition, as we all know, is something Prince Harry has always liked to do with a twist.
This was the loveliest, most beautiful chapter of a tumultuous story that has seen the young Prince walk behind his mother's coffin at the age of 12, then weathering various scandals, from teenage dope smoking to foolish fancy dress costumes and drunken partying in Las Vegas.
There was a time when it felt as if Prince Harry would be the eternal party prince, a playboy destined to spend his life falling out of nightclubs with various leggy blondes on his arm while his older brother looked on disapprovingly.
Then, in November 2016, came the confirmation of his relationship with Meghan Markle - an actress and a beautiful UN advocate - in a statement seeking to protect her from racist abuse and unwanted press attention.
If anyone needed confirmation that this relationship was serious, they had it then. His contentment seemed evident in the way he conducted himself in public. Hot-headed Harry was replaced with hard-working Harry, the royal at the helm of the Invictus Games, not to mention spearheading the mental health campaign Heads Together.
It was through this work that I encountered hesitant Harry, the nervous and boyish man with little of the garish confidence I had expected having read tabloid tales of yore.
I had thought, when I went to Kensington Palace to interview him for my Mad World podcast, that I would get a chat about the importance of talking about mental health, some practised platitudes.
Instead I met a young man who admitted to feeling "a little tight in the chest" about the prospect of the interview; a man who spoke from the heart about the times he had been close to a breakdown.
It was clear he was now in a good place - that he had found the confidence to speak out about his own struggles in the ultimate display of public duty.It surprised many in the best possible way: that, as we saw yesterday, is Prince Harry through and through.
As recently as the past few days, there was the worry that things might go wrong again, with the absent father of the bride not to mention the erratic family members.
Was Harry's big day going to be a disaster? No. It went without a hitch, and reminded us why, for so many, he is this country's favourite royal: he wears his heart on his military sleeve, and has never been scared to reveal himself to us.
It is what made the reading from the Song of Solomon by Lady Jane Fellowes so perfect. "Arise, my love, my fair one, and come away; for now the winter is past, the rain is over and gone."
Prince Harry is the ultimate example of what happens if you put your mental health first - everything else falls into place soon after.
When we did the interview, he spoke about his happiness in his new relationship. He joked about feeling like a "third wheel" when working with the Duke and Duchess of Cambridge - how pleased he must be finally to have someone of his own. He also talked to me about wanting children.
"That will bring a whole new dimension to life and a whole new set of pressures as well that I've seen William and my sister-in-law go through... I look forward to it and hope it's possible."
The wonderful Bishop Michael Curry said that "the way of unselfish, sacrificial, redemptive love changes lives... and it can change this world."
It has certainly changed the man born Prince Henry some 33 years ago. Since then we have known Harry the clown prince and the playboy who seemed unable to settle down.
Today we know him as the Duke of Sussex, Earl of Dumbarton and Baron Kilkeel. It will no doubt be his most brilliant incarnation yet.
Telegraph Media Group