As mentioned, after an easy and quiet cycle ride and bathroom window entrance, where no one had seen or heard him, he was now holding a fully loaded rifle with everyone asleep.
It should now be a straight forward massacre as my video showed the rifle with the silencer on is silent. Maybe even without having to reload. Ten accurate head shots into four sleeping people, and one into Sheila after getting her out of bed could do the job. The bedroom phone could be taken off the hook and Neville moved to make it look like he had made the call.
It didn't go this smoothly, which was a major blow for Bamber.