Two kinds of nostalgia

There are, I suppose, two kinds of nostalgia.
There's the kind involving stuff you actually lived through (Type A) being more or less inflight, infra-generational snacks and movies, or customs and films and riffs that had to happen owing to meetings that were held before you were born. It comprises whatever felt necessary or good then; or perhaps the stuff that merely does now, with the curse of hindsight.
And then there's the other kind (Type B) which involves stuff you weren't around for and wish you were.
This is the the world of contemporary Lindy-Hop enthusiasts, neo-New Romantics or dressing like a thirties poet. I don't have this kind of problem, but Type B strikes me as both more decadent (a sentimental eye trained on the fully imaginary) and more creatively interesting, because it's not just inherited.
As anyone who's been outside lately will know, we're still in the grim grip of another INSERT_DECADE_HERE revival (the third or fourth, I was glumly informed by a senior fashion editor) but this one is deeper and more real than previous hipster twitches, and takes in (it seems) a pretty wide slice of youth, from tweens to teens, nation to nation. Insofar as haircuts can bridge oceans, this INSERT_DECADE_HERE thing does. A quick age calculation will tell you that nearly all of the participants were not alive for INSERT_DECADE_HERE and are already onto the hard-fantasy stuff, Type B.
This is not exactly news in itself, not much unlike the teenage sons of Lowestoft fishermen on an Edwardian tip (the original Teddy Boys), but it's bound to be deeper, since full participation in youth culture is now, depressingly, a mandatory activity for youth.
But you will note that nostalgia for everyone is getting thicker, chewier, denser and more ornately art-directed: and like older revolutions in taste is not just inspired by a backward-looking attitude, but also by better access to better data, of better libraries, archives, style-guides and theoretically better ways-to-be bursting online: this is the golden age of let's-pretend.
So back in the High Street, it's hard not to conclude that when (and anywhen from the imaginarium will do) has finally (and definitively) moved in to replace who or where as a cultural determinant.
Now, let me tell you about Ker-Plunk some day, if you're not too busy.