Freddie was not the only person to be with her that night. Colin's mum went over because Freddie had called her, he also called Nevill. If Freddie was hiding anything he certainly did not come across as such, for if he was hiding something he would have just walked out and left Sheila alone, but instead he tried his utmost to help her. I believe he also called one of the children's parents to come over. This episode lasted all night long and do not think that Freddie would have made the phone call up, he had no reason to lie about it. I'm not sure but I think 3 doctors attended to her or tried to through the night.
I often wondered if the same thing happened at WHF....Did she catch NB on the phone to Jeremy? Was this the beginning of another episode? I am speculating, but its quite possible. 
The whole point is that in her past episodes she didn't wake up deranged and go around waking up others and disturbing them. It should be remembered her past episodes were prior to being treated and when she stopped taking her medication.
Freddie claims the frustration from a phone call being disconnected set her off and then she got progressively worse as the hours went by and ultimately only Nevill was able to calm her down. He is the only one she recognized and she instantly calmed down enough to be able to talk coherently.
The allegations from Jeremy is that Nevill called to report that Sheila had gone crazy and had a gun and was asked to come over to help handle her. She already supposedly was deranged and had the gun before the alleged phone call. No one else would be awake at 3AM for her to interact with and become deranged while interacting with. Sheila would have to have woken up deranged and then woken June up. She was a light sleeper while Nevill was a deep sleeper plus she was closer to the door.
The only one not shot while in bed was Nevill and he could have been sitting on the bed when shot. That could explain why the shots were all to his left profile. The shot to his shoulder had a down trajectory but shouldn't if he was standing upright when shot unless the killer was standing at a higher location than he was. So this suggests he was sitting or bending not upright fully when shot.
The initial encounter was in the master bedroom where the killer shot June at least 6 times and Nevill 4 times. It is hard to come up with a reasonable scenario where Nevill would have made a call to Jeremy, hang up the phone and then take it off the hook and then returned upstairs to the bedroom so that both parents could be shot together. The phone call is not credible. The killer entered the master bedroom and shot both parents, then gun was empty before Nevill could be immobilized and then either the killer ran to the kitchen to reload with Nevill giving chase or Nevill ran to the kitchen to grab a weapon or to escape through the door and the killer gave chase.
The bottom line is Sheila would have to have woken up deranged then disturbed the others which prompted Nevill to call Jeremy as opposed to the others already being awake the same time she was and interacting with them resulting in her becoming deranged.
