Yes, quite right,
Bamber was set on killing his family months if not years before the event. I do believe that there was a trigger. As often is the case with cowards, they like to morally justify what they are doing by creating a pretext. This way they can often justify - however ludicrous it may seem to us - their actions. Bamber often justified the killings to Mugford later by stating how "mad" or "passed it" they all were and that he'd "done everyone a favour"
I believe Bamber manufactured an argument the night of the killings, between himself, Sheila and his parents. The pretext was probably the notion that the parents, noticing that Sheila was struggling physically, emotionally and financially, wanted her to live closer to them so they could keep an eye on the boys. It is reasonable to assume that they asked Jeremy about maybe giving up his cottage (which belonged to them) for Sheila to live in. This would have incensed the selfish Bamber. The farmhands living nearby heard Bamber slam his car door and screech his tyres as he left. This served dual purposes. Not only was he angry but he also had the cunning insight to send a clear message to those still on the farm -such as Len Foakes - that he had left the farm. This spat was what he'd been waiting for - justification of a sort. It was later that night that he'd phoned Julie and told her he was "pissed off" He was working himself up, like any coward, to summon up the guts to kill his family. He didn't need any help, assistance or urging though. The time was right, the family had finally gathered in one place. "Tonight's the night"......."It's now or never" and this coward knew it.
