The guilters rarely consider Jeremy's likely state of mind on 7th August if he's innocent.
They usually assert or imply that Jeremy, if innocent, must have been woken by Nevill at about 3:10am. If Jeremy is innocent, that doesn't make sense, as we know very little about why Jeremy said 3:10am and so it shouldn't be assumed that time is accurate.
In Jeremy's statement of 7th August, he says Nevill called him at about 3:10am, but doesn't state how that call ended, then he says he immediately tried to call Nevill back, but got the engaged tone, and then he says he immediately phoned Chelmsford Police to inform them of what had happened. If Jeremy was guilty, that makes no sense, as it would be easy for EP to prove that his summary was quite inaccurate. Also, it forms a poor alibi. If Jeremy was innocent, the timing still can't be right, but an explanation is available - Jeremy didn't know at what time Nevill called and estimated it incorrectly, then he oversimplified what happened after that, and twice used the word "immediately" inaccurately. That's understandable, given his likely state of mind at the time, and that he was close to concluding his statement. He gave very little detail about his conversation with Pc West in the statement, and no indication of its duration.
On the basis of the above, it's clearly unreasonable to say that Jeremy was stating he phoned Julie after phoning the police. Jeremy continued his statement by saying he then went to WHF, where he met the police and went with them to the farm house and heard a dog whining, and then on police advice everyone backed away from the house. This was again a highly simplified account, omitting many details (which is odd if Jeremy was guilty). At this point, Jeremy states "I phoned my girlfriend up from my house at 3:25 a.m. to tell her something appeared wrong and I again phoned her at 5:45 a.m. from a telephone kiosk to inform her what was happening and not to go to work as it was evident at this stage that something was wrong." That's how his statement ended.
What seems to have happened is this: after some conversation with the police, Jeremy gave several pages of information about various earlier events and circumstances because the police didn't already have that information. Then he gave a highly simplified and shortened account of what happened from the time when Nevill called him, possibly because there seemed to be no need to go into lots of detail about things that the police were largely aware of anyway.
Note that for some reason EP haven't released the original handwritten version of Jeremy's statements, so we don't know whether the typed versions are accurate. Jeremy intimated that he thought they weren't in a letter he sent to mike tesko. We know that Ds Jones later claimed that Jeremy had said verbally that he'd called Julie after calling the police, but we can't check that conversation.