Not sure if it counts as a classic, but having seen both the 1953 Young Bess movie on TCM and having read the book by Margaret Irwin about the young Elizabeth I, I find the movie to be quite disturbing, considering that it essentially romanticizes what was most likely a case of sexual abuse perpetuated by Thomas Seymour against Elizabeth. Not only per modern historical consensus, either. The book itself, written in 1944, portrays Seymour as manipulative and abusive. Seymour wasn’t exactly her stepfather but he did marry Catherine Parr, Henry VIII’s 6th wife, after Henry VIII died.
Now certainly a remake of that, even one that stuck to the original book that is not at all explicit, would be interesting, because recent movie treatments of Elizabeth have portrayed her as a strong woman and showing her as an abuse victim might be controversial to say the least.
It’s interesting that for all the agita about how sexually depraved modern society is, there are certain taboos that are actually stronger than once before, and taboos against child grooming and relationships with extreme power differences is one of them.
Gigi that was adapted from a book into a musical, and then into a film in the supposedly chaste and wholesome 1950s, also romanticizes child grooming and I know a recent revival of the musical aged Gaston DOWN and also had “Thank Heaven for Little Girls” sung not by Gaston’s uncle, but by Gigi’s grandmother, in order to tone down the creepiness factor, though IMHO not by much, as the grandmother is happy to pimp out her granddaughter to Gaston. In a way it’s worse because it then becomes a song actually advertising little girls as eventual sexual objects, as opposed to just being about a dirty old man showing what he is.