'Why would Sheila have done it and not inherited because she's dead ? Would she have done it to ensure JB got everything ? Nope.
The only gain out of this, of course, was JB. So he had the motivation to murder. He was bragging about what he was to gain i.e. the caravan site is about to buy me a sports car. Or words to that effect.'
Nobody has ever suggested a rational / greed motive for Sheila - if she did it the only possible explanation can be psychosis. She loved her sons and had a good relationship with her father and would have had to be a long way divorced from reality to kill them.
Re the sports car, I believe JB on this one: he says he was talking about a kit car, not an actual Porsche, which he could have bought out of the next payment he was due as a director / shareholder of the caravan site. The kit car company has confirmed he had been in touch earlier, but he didn't know it was going to be brought up in court so didn't have a chance to get the statement.
As far as I can see there was a fair bit of stuff said in court which was wrong, or dubious constructions put on innocent things. If Bamber was guilty, but he knew some of the prosecution's claims could be disproved, it makes sense that he would have consistently claimed his innocence and been confident that sooner or later he would win an appeal.