There is more to it than just the glass also Eleanor. A bowl of sugar had been upset onto the floor. It would also be inconceivable that a barefoot Sheila didnt manage to pick any of the glass or sugar up on the soles of her feet, especially when she is supposed to been in a vicious fight with her father in the kitchen. Put succinctly, she was not in the kitchen. Nor was she in a fight with her father - there is absolutely no evidence of either event happening whatsoever. This of course has enormous implications for Jeremy Bamber who claimed on the phone to a police officer that 'My father just phoned, he told me that Sheila has gone crazy and has got the gun' With this statement Eleanor, Bamber made it two horse race. It was either Sheila (if you believe Bamber's version of events) OR he was lying about that phonecall. The only possible reason for Bamber to lie about that phone call can only be that he was involved. There is no other scenario. Now if we look realistically at the evidence of Sheila's possible culpability, it amounts to absolutely zero. No blood on her pristine nightdress (inconceivable if she's just been in a brutal fight with her father) No debris on the soles of her feet (equally inconceivable if you couple this with the first point)
and she had managed to shoot herself twice (this is theoretically possible at least, but I do not believe she was conscious after the first shot - a sub-sonic bullet travelling into her chin at that speed would have knocked her unconscious, considering that the hardened chin of a heavyweight boxer meets the same unconscious state with just a fifty pounds of concussive pressure applied to the same area)
In sum, Eleanor, Bamber made his fatal mistake with the story about that phone call. It instantly closed the notion of any other person being responsible but Sheila or himself, and as we have seen she could not have been involved.
Bamber is undoubtedly guilty.