Mick, Keith, Charlie and Ronnie (them what's left of the original band to play on the current Voodoo Lounge tour) have become the greatest of all all-round family entertainers. "It's only rock'n'roll," bawls the future Sir Michael Jagger from the stage in faux-cockney-meets-Memphis Tennessee, "but I like it," - at which a grizzled dad alongside me at Wembley Stadium on Tuesday night draws out his mobile phone and calls home to see if the kids are all right. Mick - pop star as family man - would understand all that stuff about babysitters, nannies and trust funds.
It isn't hard to tell apart the parents (sporting vintage-Stones T-shirts listing gigs they've rocked to from Hammersmith to Hanoi) from the kids who have escaped bed and are grooving to songs first performed when mum and dad were at primary school - make that prep school.
The couple in front of me neither rock, shimmy, shake nor even tap their toes; nor do they applaud a most under-worldly "Sympathy for the Devil". Stiff as a ramrod, the wife brays above the roar of "Jumpin' Jack Flash" (he's a gas, gas, gas), "Catriona is expecting us for supper at nine sharpish tomorrow, yah?" "Yah," replies her lantern-jawed hubbie.
The vast crowd might look superficially American (Midland, Texas-kind of American), but beneath the T-shirts and baseball caps it's doggedly English, whatever the age, income and social strata. The fiftysomethings on stage have had to work hard to get us thirty and fortysomethings off the phone, away from work, prepared to give up the supper party-babysitter talk and to wiggle (just a little) in time to the 4:4 beat.
I first saw the Stones as a child in a raw, smoky club when they seemed as mean as the Sex Pistols did in '76. I saw them again in Hyde Park (still as a kid), when they were in their dresses'n'psychedelia mood (redeemed by "At Her Satanic Majesty's Request"). I caught them in 1982, when they were slick and simmering but a little off the boil. On Tuesday, in the vastness of Wembley Stadium, they proved (with a little help from a phantasmagorical stage set, magical lighting and a superb video system that could take you right up on stage with Mick, facing the audience) that they could easily kick Blur and the rest into touch.
Jagger's age-defying performance and the fact that nearly everyone can singalonga-Mick (these are the pop anthems of the past 30 years) couldn't fail to get the audience to its feet, even if at least half of them were worrying about the time of the last train home. The joint finally jumped and, a day later, the audience is probably proudly, gingerly, feeling its aches and pains.