Exhibition: Cover Story - Radio Times at 90, Museum of London
Where do the private views and public discussion intersect most often and most favourably. Politics? Maybe - but it's not one for a decorous dinner table. Best sandwich fillings? Perhaps - but as the answer is egg mayo where's the debate?
No, the answer is still likely to be that old watercooler standby, TV.
Television viewing habits are personal but they are exported like Instagram snaps into the wider world for dissection and discussion.
Not what it was, of course. When Blitz-weary folk huddled to ITMA for laughs or Den delivered divorce papers to Angie in the Vic but television still occasionally finds the tipping to bring together the country in common cause.
Broadchurch was an example; national events such as the Olympics always work; The Apprentice and other reality shows might follow the laws of diminishing demand but they can still break ice in an awkward elevator moment.
The unveiling of Peter Capaldi as the new star of Doctor Who on Sunday was indicative that TV still has the power to coalesce an audience - because of, not despite, the proliferation of social media.
So the Radio Times, 90 years old this year, could be viewed as a microcosm of our cultural mores, as a new exhibition sets out to show.
Just a listings magazine, but the 4,500 covers provide some key social signifiers from the Reithian patrician outlook of the '20s to the shackle-free hedonism of '60s and multi-channel explosion of the present.
That the Radio Times has survived at all is a near miracle. We can watch what we want when we want to the point that listings appear fuddy-duddy. Meanwhile, print publications in any form are an endangered species in themselves, regardless of content. Yet the RT sells a million a week and is as much a part of Christmas as the acts who appear on the covers.
Cover Story: Radio Times At 90 shows covers through the ages and picks out some defining themes that bury deep into our social fabric.
It hijacks Dr Who, itself celebrating an anniversary, and makes the point that the time traveller and his foes have been cover stars more times that the Queen. There's even a Dalek.
Until Nov 3, FREE, museumoflondon.org.uk.