How do you know he didn't calm her? He may have calmed her thrice during the night for all you know. Yet again, another attempt to impose your specific rationale, upon a desperate and irrational situation unfolding.
You see I don't accept the Defence's telephone call in the first place,so it's again building one hypothesis on another,if you can put yourself in the shoes of the Prosecution for one tiny moment..
There's just no way that Sheila was the type who would go berserk or go crazy or whatever words you want to describe it with a gun. It was Jeremy who loaded the gun with a magazine don't you see,because he knew that people would say Sheila could never have performed that action,but Jeremy could not predict exactly how much ammunition he would need to kill five people in a rifle whose purpose was to kill vermin.
I don't accept the suggestion that somehow Nevill manages to calm Sheila down,then she kicks off again. It's quite clear from the way the bullet cases are scattered that Nevill is shot on the landing yet manages to make his way down to the kitchen, whoever you think the identity of his assailant is,and in these circumstances everyone's natural thoughts are to telephone the Police. Why wake Jeremy up anyway in the middle of the night when he might after all not even pick up the receiver?
It's not just at the White House Farm end that the Jeremy supporters' scenario breaks down. We have Jeremy calmly flicking through the Yellow Pages for ten minutes,as well as telephoning Julie(we won't go into the exact timing of that now as that represents another headache) as we are supposed to believe his words to the Police: "what's taking you so much time..my father sounded terrified when he called" yet Jeremy retracts this at trial which along with other inconsistencies in his evidence make his version of events incredible and the jury's verdict of beyond reasonable doubt a correct one.