Nice one Caroline. A new thread which issues a real challenge. I like it

Where to start? I guess by saying from the start that the only person who will ever know the truth is Jeremy and as a result, I'm not one of those who will ever be 100% convinced, EITHER way and my decision is based on what Steve would call a "balance of probabilities"
Young men in Jeremy's mould are ten a penny here in Bamber country. Easily picked out by their accents, they can be found, large as life, socializing in Young Conservative and Young Farmers' clubs after having left schools such as Felsted, Framlingham, Stowe and Hailybury(?) of which there are a surfeit in the area. They all carry about them an air of entitlement, inculcated by breeding and education. They do whatever is the modern equivalent of the Grand Tour, always funded at SOME level by parental generosity and if some sort of work is required to keep them going, parental "connections" can be used. After a year or two, they return to the family business, where even if the pay wasn't "up there" the perks undoubtedly were.
This, then was the background to Jeremy's life. He would have had dreams. What young man doesn't? But whatever life he may have yearned for, it doesn't seem to have run him into any kind of debt. He seems not to have been afraid of taking odd jobs to swell the coffers and was in credit at the time of his arrest, since when NO ONE has come forward to say that he owes them money. Almost EVERY penny of what he earned was HIS. There was probably very little by way of domestic expenditure that wasn't attached to the farm business. It was pocket money.
So what was Jeremy like, as a person? Depends on, as it would for the rest of us, to whom one is speaking. Boarding school life isn't a million miles away from forum life. It's inhabited by all comers who AREN'T all going to hit it off and is very much about the survival of the fittest and HOW one fits in. Jeremy may NOT have, entirely. There are always those who don't. However, there are no reports of unacceptably bad behaviour so it would appear that like the majority, he muddled through and was probably one of those who rarely stood out as doing anything remarkable. He may not have been an academic star but he didn't get expelled. I suspect that his desire to impress would have been an irritant to some. I have NO hesitation in suggesting he was a boaster and a braggart as the immature SO frequently are. His childish "bon mots" were eventually used against him but had probably been little more than the less artistic version of throwing Shakespearian quotes into a conversation for effect, the desire to impress his girlfriend's mother.
I suppose if the rellies could convince themselves of his guilt, it's possible for others to convince themselves of his innocence but on a balance of probabilities, I don't believe there is anything about his life prior to the murders to indicate that he either felt the need to or was capable of such an act.