I will upset some adoptees here again I'm afraid but Jeremy Bamber was born in Kensington,London and had city life flowing through his veins. How he must have envied the flat his parents bought Sheila in Maida Vale,if not her lifestyle. When he realized that Sheila had become ill and was struggling with everyday tasks such as putting beans on toast,and cast an eye on his adoptive parents: Nevill who was off work from his magistrates' job with stress and June who would burst into tears most days, who were both ageing however much deep down they loved him,I think Jeremy began to see how he in his mind could "do everyone a favour",especially when he saw the twins clinging to Colin at the party and made that infamous comment "they're a millstone round your neck".
You're right about Jeremy not being fully aware of things because he saw them from his warped angle and which ultimately proved to be his downfall. Nobody can seriously expect Sheila to have been in any kind of struggle with Nevill which left a ceiling light broken and Sheila intact,nor did Nevill the former RAF pilot relinquish the telephone without some exertion on his part,even if was only leaving his bloodied prints on the blue and white chequered worktop and hiding his watch under the rug.