Henry James: The Turn of the Screw

The mysterious aspect behind this famous ghost story (published in 1898, but referring back to events of the 1860s) would seem to be not so much "were the ghosts of Peter Quint and Miss Jessel actually there?" but "what precisely had been going on between them and the two children, Miles and Flora, over whom they still exert some kind of a hold?" We are never told the answer to this. Words like "evil" and "horror" are constantly being used, but are never explained. Miles, we are told, has been expelled from his prep school for telling certain "stories", which upset the other boys and appalled the masters, but once again, we are never told the nature of these "stories".
We as readers are of course free to place whatever interpretation we like on the novel, but at the same time we must wonder what exactly Henry James had in mind when he wrote it. My suggestion is that it is concerned with sex, a topic which James, a lifelong batchelor, was always reluctant to write about directly. Had Quint and Miss Jessel been caught "in flagrante" by the children, who were then sworn to secrecy by the threat of dire punishment? Or was it, more darkly, that this pair had been sexual abusing the children? Obviously we shall never know what James intended, but I think that, if we assume sexual abuse of the children, that explains the underlying mystery of the novel better than any other theory. The constant references to evil and horror, Miles's disgusting stories, the strange hold that Quint and Miss Jessel still have over Miles and Flora, all fall into place.