Anyone who has remained in power for longer than many people remain alive — even if that power is far more symbolic than practical — is worth paying attention to. And when it comes to England's Elizabeth II, paying attention is something the world has been doing for a long, long time.
"Her current Majesty," TIME's Belinda Luscombe once noted, "is very likely the most portrayed woman on the planet. Billions of stamps, millions of coins and notes and hundreds of thousands of postcards bear her likeness. Her face, especially in profile, is recognized in every English-speaking land and is ubiquitous in several. Hers is not the exotic, come-hither face of a Marilyn or an Angelina. It's the face of distant historic authority, a literal figurehead, having no real power but oodles of symbolic supremacy."
Here, LIFE.com offers a series of informal portraits of the Queen, including several that never ran in the magazine. And while some of these images do convey "oodles of symbolic supremacy," it's also worth noting that, in at least a few of these shots, there's also a flicker of something that one hardly ever associates with Elizabeth: namely, a quite self-aware and yet wry sense of fun.
Now that's something to celebrate.