The way I see it, the rifle was removed from Sheila's body on three separate occasions, once by 'Ivor' Montgomery, secondly, by 'Ron'Cook, and lastly, by PS Woodcock...
The key event, being the removal of the rifle by 'Ivor' Montgomery, from Sheila's body prior to the crime scene being handed over to SOCO ('Ron' Cook, 'David' Bird, 'David' Hammersley, and 'Neil' Davidson) at 10 O'clock, and the taking of photographs, in particular, with the rifle back on the body, after 'Ivor' Montgomery, had already taken the gun away...
The sequence of events which I have outlined here, supports the argument for the police having stage managed Sheila's body, the rifle was put back on the body after 'Ivor' Montgomery had previously taken it away. Sheila's body and the gun upon it, as shown in the photographs taken by SOCO 'David Bird after 10 O'clock, cannot be the same, uninterferred with pisition she was originally found in by the raid team, because the rifle has clearky been offered to the body (Woodcock), removed from the body (Montgomery), and offered back onto the body by one of the senior officers present inside the bedroom when Woodcock discharged a loaded rifle into the victims brain...
According to David Shaw, DCI 'Taff' Jones was the person who was offering a broom handle onto Sheila's body, with the view of gauging the angles at which the two wounds on her throat could have been discharged almost simaltaneously, but the information I have been given, is that he put the actual rifle back on the body, and gave instructions to SOCO to photograph the body with the rifle positioned on her body for the purpose of satisfying the coroner that Sheila had killed the other victims and then taken her life with use of the rifle...
This, is what really did happen...