Yes, as a UK person of late Gen X I don't think I encountered this at all as a child. Depressing UK children's lit at the time was heavily social realist with protagonists who were too ground down or streetwise to come up with elaborate fantasies. The closest I remember was a novel I read at school which had a heavy plot element about a Alien Big Cat on the moors near where the protagonist lived, but whether it existed or not was left ambiguous and it was more symbolic of the protagonist's inner "wildness" than anything else.