150 words is too few for me to outline my own theory. I would not have made a good journalist - lawyers are always long winded! Here is my view:
Sheila experienced a psychotic episode triggered by the drastic reduction of her Halperol dose coupled with the suggestion by Nevill and June that the twins should be fostered. At around 3.00 am Nevill was woken by sounds of movement. He went downstairs and found Sheila in an agitated state holding the Anschutz rifle. Nevill tried to calm her down but she ran upstairs. Nevill telephoned Jeremy and asked him to come to WHF. Nevill believed the situation could be contained as had happened with similar episodes when Sheila had lost control. Whilst on the phone to Jeremy Nevill was alarmed by a sound upstairs - possibly a shot was fired. He dropped the phone and ran upstairs into his bedroom. He saw that June had been shot in bed by Sheila. Several shots had been fired. Sheila turned the gun on Nevill and shot him 3 or 4 times, causing him extreme pain and incapacitating him. Nevill was then not in any condition to restrain Sheila physically. He fled back downstairs, possibly hoping to activate the panic alarm or to call the police. He reached the kitchen but overcome by his injuries he slumpted onto a chair. Sheila shot Nevill again, emptying the magazine. She then struck Nevill around the head with the butt of the rifle. She then loaded 3 or 4 rounds of ammunition into the rifle and fired further shots at close range into Nevill's head, killing him. She loaded the rifle again with 3 or 4 rounds and went upstairs. She found that June had managed to get out of bed and had reached the door of the bedroom. She fired further shots which killed June. She went downstairs again and loaded further rounds into the rifle. She went back upstairs into the twins bedroom and found them still asleep. She shot them both in the head, using 7 shots. Sheila then had a shower, putting the clothes she had been wearing into soak downstairs. She put on a clean nightdress. She wandered about the house and in due course saw the police from an upstairs window. She leaned the rifle against that window. Shortly before the raid team forced an entry Sheila went back downstairs with the rifle, possibly in order to reload. She lay down on the kitchen floor and fired a shot into her neck. The shot rendered her unconscious. When the raid team entered they saw the bodies Nevill and Sheila, who both appeared to be dead. They took steps to search the rest of the house leaving no police officer in the kitchen. Sheila regained consciousness. She got up, picked up the rifle and went upstairs. She went into her parents' bedroom, lay down and shot herself again, this time fatally. Hearing the shot police then rushed into the bedroom and found Sheila. They removed the rifle from her body and checked for signs of life, changing the position of the body. Realising that they had messed up the raid they panicked. They repositioned the body and the rifle. They agreed that they would not mention originally seeing Sheila in the kitchen.
Much of the above is founded firmly upon available evidence. Some detail is obviously speculation but in my view is consistent with the available evidence. I accept that there are other tenable explanations but overall I belief this one is the most likely.
