"Suddenly No. 9 hurled a book to the floor between his chair and the window, and, looking, I saw that it was The Rose-Lady and Trevelyan, one of the best-selling novels of the present day. And then the critic or Philistine, whichever he was, veered his chair toward the window, and I knew him at once for John A. Pescud, of Pittsburgh, travelling salesman for a plate-glass company--an old acquaintance whom I had not seen in two years."

Particularly in Germany prior to WWI, an anti-illectual,
often anti-Semitic. Heine used it frequently.

Philistines, so used (anti-intellectual), were against intellectuals as a class or simply against any kind of academic achievement?

In the common use of the word here (the UK, particularly in the writings from the early part of the century), Philistines weren't necessary opposed to intellectuals: a Philistine was anti-intellectual in the sense of having a coarseness or insensitivity to the more refined aspects of culture - art and so on. So the word was frequently used synonymously with boor.