The defence suggesting Nevill phoned before being shot, was not an option.
They would have to make up a scenario of how after the call, Nevill then allowed Sheila to get upstairs & then allowed her to shoot him 4 times upstairs, twice from close range in the face.
This would just undermine the defence case as there is no credible scenario. It would also show they did not believe Nevill rang after being shot 4 times.