George Barwood seems to believe that Nevill called Jeremy before being shot and then presumably went back upstairs to be shot by Sheila and then came downstairs again to be shot again and killed.
No idea of the events and can not rule anything out.
He may have made the initial call not on the kitchen phone.
It's perfectly feasible that an injury to his mouth rendering him unable to speak came after the phonecall to Jeremy.
He may have attempted to use the kitchen phone in the kitchen onslaught.
This is not a pro Bamber argument from me. This is just mere fact.