Murders all done, cleaned himself if he needed to, then the phone scam. Have to assume Bamber knows within a minute or two how long it would take to get from WHF to his cottage, obviously using the quickest route with the quickest mode of transport.
Nevill dying in the kitchen dictates the location of the call to the cottage. But Bamber has to be ready to go once he ends the call. Think Bamber knew or thought he knew that calls could be traced so the quicker he gets back to the Cottage the better.
Makes the call, waffles into his answer machine, leaves the phone off the hook, making it look like Nevill was under attack. Gets back to his cottage, wipes answer machine. Should've phoned police ASAP. Why he phoned Julie, I can only speculate, could be put down to stress, panic, may be trying, as I have said, to calm himself before starting the frame up scam.
Answer machines don't start recording till after 6-8 rings or whatever they are set for.
Other issue is, it has been established I believe that Nevill was shot in the face more than once in the bedroom. How then is he able to dial Jeremy and speak in a clear enough voice and also do this whilst under attack from Sheila.
Did Bamber really think this phone scam would work. For it to work he needed an accomplice to impersonate him calling the police from his cottage, a few minutes after the Nevill call. The time delay from the Nevill call and the call to police from his cottage scuppers his phone scam.
