The bible was also June's, which supports a frame.
Bamber knew the bible was there. He said he may have used it to swipe Crispy with. So he simply used an available bible, which was not Sheila's, to assist his staging attempt.
Now if Sheila's own religious book, which she had brought with her to WHF, was found next to her, that would be more plausible. Bamber could claim he didn't know this book existed.
There is no guarantee Sheila knew where the bible was, or that she would remember in her psychotic rage. Or bother using it.
This and my other three posts on the bible, above, have again shown without doubt that Bamber is guilty.