Consider, for example, the group of French composers collectively dubbed Les Six. Naming all six of them has long been as ticklish a proposition as naming all seven of Disney's dwarfs, but the reputations of even such former heavyweights as Milhaud and Honegger have declined to the point where not just pride of place but sole place has been ceded to the deceptively frivolous Poulenc. Or take the "Mayhem Parva" school of classic English whodunits. Allingham, Berkeley, Sayers and Dixon Carr still doubtless have their faithful readers but, for the wider world, the whole cosy coterie has shrunk to a single member: Agatha Christie.
The same process has surely been at work on the band of ground-breaking dramatists, the so-called Angry Young Men who sought to revitalise the British theatre in the 1960s, substituting the kitchen sink for the French window as its emblematic prop. At the time they were all pretty equally esteemed: Pinter, Osborne, Delaney, Arden, Wesker, Jellicoe, Mercer, Rudkin. Thirty-odd years on, the only one who can claim to belong to the ongoing present tense of our cultural life is also, not by chance, the only one who mapped out a hitherto unexplored theatrical terrain: Pinter, of course.
As for John Osborne, who actually launched the movement with Look Back in Anger and who would probably have been voted by critics the most likely to survive, he has become a specialised taste, of interest to those who continue to be passionate about the theatre, of indifference to those who are not. His plays were monodramatic rants as dated as the events and issues in reaction to which they were written; his language was indistinguishable from that of his peers. There's no such thing as an "Osborne sentence", still less an "Osborne silence".
Pinter's name has become an adjective, "Pinteresque", whose meaning we all understand even if, like his own characters, we sometimes find it hard to put into words. But "Osbornesque"? Posterity will look back on the Osborne cult not in anger but in bafflement.