Do You Know Why Moaning Myrtle in 'The Chamber of Secrets' was Played by a 36-year-old Actress? The Film Doesn't Explain, but the Creators had Their Own Plan

Many fans had questions, but now they will definitely disappear from the radar.
In Harry Potter and the Chamber of Secrets, Moaning Myrtle whines, slams toilet doors, and acts like a typical teenager. She seems to be 14 or 15 years old, like the other characters. But the actress who played her was... 36 at the time of filming. Yes, almost like Professor Trelawney. Why is that?
Shirley Henderson, who played Myrtle, looked youthful, but it was hard to hide her age. And this is not a casting incident. On the contrary, the creators of the film deliberately chose a woman almost twice as old as the character. And the reason is not that they could not find a suitable schoolgirl.
The thing is that Myrtle is a ghost. She died at Hogwarts decades ago, and has not changed since then. But a teenage actress - in the two years between films, she is literally unable to fit into a school uniform. For Goblet of Fire, they needed the same Myrtle as in Chamber of Secrets, not an older version. And that's where age stability comes into play: an older actress ages much less noticeably.
From Comedy to Tragedy
Interestingly, Henderson is not just a random choice, but a theater star with a tragicomic gift. Myrtle in her performance turned out to be on the edge between a comic hysteric and a tragic spirit, stuck between the world of the living and the dead. A schoolgirl would hardly have pulled off this balance.
Result: a ghost with experience
So no, this is not a bug. This is the director's foresight. After all, in the magical world of Hogwarts, age has long been relative - and who said that the spirit of an offended girl cannot be played by an actress who has experienced more than Harry himself?