That, behind the glitz, they're just plain folk like you and me and all the glitz is just an act for the fans. Off stage, give them apple pie, Mom and a good movie anytime.
Problem is, we believe most of them, because it's easy indeed to believe they are really ordinary, exactly like us.
But whatever view one has of them, the same can't be said for the Royals.
Like them or loathe them, force of circumstance, privilege and familiarity makes it impossible to imagine them down the Mace for a pint of milk or squashed in beside you on the plane to Manchester.
Which makes it all the more touching that William and Catherine were spotted in the queue for The Avengers down their local Odeon in Kensington.
Touching, partly because it's such an 'ordinary' thing to do; also because it's such a romantic thing to do and they're only wed over a year; also because it's such an old-fashioned thing to do (they could easily get a By Royal Request DVD and watch it at the palace).
But it's also nice because it does mean that we do have an advantage over them after all, for all their wealth and status.
We can go to the pictures anytime and no one bats an eyelid. No one wants to kidnap us, unless we have a particularly stubborn ex.
Fair enough, we won't ever get to 'big it up' for a weekend in Windsor Castle before returning forever to our own wee heavily-mortgaged leaky hoose.
But maybe, the same way as occasionally we might fantasise about being a king or a queen (or both, who knows?), Royals might just wish, just once, to be as anonymous as we are. They'll never have our hairdresser, of course. Or our jalopy of a car. But it does show that our own state in life might not be quite as bad or dreary as we often think it is. Not so bad at all. Popcorn anyone?