It does seem strange that Jeremy or anyone else would have confided in her with something of this magnitude, while playing the field, so to speak. That bit never added up.
I've been saying that for months. It's daft. In my opinion, the only way he would confide in her is if she is in on it. In on the deaths. In which case, as has been suggested by SteelMagnolia blog, his phone call to her is an attempted alibi for both of them. She then cannot stomach the results and turns him in. This scenario is possibly undermined though if he plays the field as you suggest Sparks. The only way that could hold water, again in my opinion, as if he is effectively saying to her 'look, there's f*** all you can say, you were in on it too". In which case he was sadly mistaken.
I think a useful thing to do is to try and put yourself in his shoes (as the murderer). It absurdly audacious, to execute five murders for inheritance, while retaining virtually no forensic link to the scene of crime, absolutely none on your person or in your home or in the surrounding area, in the time space in which he had to complete this grisly task. Conversely, given that the whole point of the murders is for inheritance, it is unrealistic that he would have an in built 'go to jail' clause in his plan, by spilling the beans to Mugford before and after the event? "Darling, I'm just off to kill my family. I'll call you when its' done".
Posters on here go on about defence conspiracy theories, as if there's never ever been any conspiracies in this country. As Ann Eaton might say "poppy cock".
Sorry for overusing the word... But the prosecution case is absurd.