"I hated historical novels with fluttering cloaks"

This quote by Jeanette Winterson is a commentary on her distaste for historical books. She is revealing her dislike for the genre, which she thinks is often extremely glamorized and melodramatic. She particularly discusses the use of "fluttering cloaks" as an example of this, suggesting that these novels typically count on cliched and exaggerated imagery to develop a sense of drama and love. Winterson's quote implies that she thinks these novels are too concentrated on producing a romanticized version of the past, instead of precisely portraying it. She is most likely suggesting that these novels are not realistic or precise, which they are more concentrated on developing a romanticized variation of the past than on accurately portraying it.