The Royal decree was to take a photo, of anything, regardless of subject, but to ensure it was on the day itself.
Even better, she said (I quote) "And you don't even need to use your camera: take it on your phone while you're out and about."
Aaaahhhh. Woman after my own heart. She knows me too well by now.
So, I could have posted a delectable selection of holiday-inspired items snapped on the day itself, like this:
Widget's amazing boogie board balancing act
Sunday's lunch location
Sunday lunch - view from beach restaurant
But ultimately, this one sums the day up perfectly: