I have a memory of watching something where this child and crew get shipwrecked on an island. The child falls in love with a woman who was with the crew but she gets taken away (maybe by pirates?).
There is a blind old man who was already on the island (seems dressed like some early 20th century gold digger). There is also a butler with the kid who hates this blind man.
At some point near the end this butler tricks the old blind man into falling down a deep hole (maybe to his death?).
Meanwhile, the kid finds some magic thing (maybe a trunk, maybe a mirror) that transforms him into a grown up so he decides to follow after the woman on a boat he found (with a dog?). He leaves the butler on the island, trapped because he forgot about him?
I also think this is a story topped and tailed with a parent reading to their child.
This was a long time ago and I feel like I remember it but i have not found anything with internet searches.
Pls hlp.