Diversity is what will kill crosswords, and I don't mean diversity in the skin color or gender of the setters, but the fragmentation of culture where nobody watches the same TV channels or reads the same newspapers any more. We increasingly hive off into our own bubbles of preferred content, tied only by whatever cultural commonality we acquired in grade school.

There's just too much art, too many books, too many TV shows, and too much access to it all, to go back to the mostly-shared corpus of mostly-mutually-understandable cultural references we had in the 20th century. You would think that people would at least have read the really famous books, or seen the super popular TV shows, but I am regularly surprised to meet people who haven't.

Fair clues are foundational to crosswords, and foundational to fairness is understanding what the solver can be expected to know.

A Guardian crossword last week referenced The Beatles, Anthony Eden, and the Russian revolution. Fair game? All part of a standard British upbringing, surely? Perhaps for now, but for how long?