Some interesting theories here. I don't know what the position would have been if the twins had died last, inheritance-wise, it depends on whether there were 30-day clauses in the Wills. Would it have been assumed that Sheila died last even without the testimony of Julie Mugford? If so, then anything she inherited from her parents who died before her (excluding a 30-day clause) would go to her next of kin - her grandmother.
As the assumed murderer I think Sheila would have not inherited anything ...
A strong principle in UK law is that no person can benefit in any way from a crime they commit ...
So it would be assumed that as the youngest the twins died last and Colin would have inherited a big slice ...
This principle also explains why it was so important for Robert to see Jeremy convicted of the murders ...
Jeremy's conviction stopped him from inheriting in line with this legal principle ...
So to Robert (a known will fraudster) it was important that Jeremy was convicted and that there was some evidence (Julie's "remembered" statement) that the twins died first ...
It makes no sense (other than to a deranged Sheila perhaps) for anyone to shoot the twins before Nevill ...
Julie did not "remember" Jeremy telling her the twins died first during 4 days with Police ...
Julie was telling lies that Robert Boutflour asked her to tell ...
The truth is easy to see when looking at these details ...
Robert was a known liar (he lied in court about the money and lied to grandma Speakman about Jeremy having died)
Robert was a known will fraudster (his lies to grandma Speakman about Jeremy dying)
Robert was behind the planting of the silencer ...
Robert was behind Julie's lies to the Police ...
His motive was very simple - money ....