Why would he risk breaking in unarmed waking crispy up eating Neville to an intruder, then rummaging round for a gun in the dark with a dog yapping at his feet? Neville would of been downstairs like a shot and possibly could of found the rifle before Jeremy, if Neville moved it, he knew where it was, Jeremy didn't.
The bathroom window was loose or already ajar.
Crispy was not guard dog. Asleep & maybe locked in another rooom. Thread created.
Nevill was in bed asleep. It was 2am.
Bamber knew WHF & knew where the rifle was.