Why are you focusing on SB? There are about 6 people who give varying times on when Bamber called Julie.
The reason should be obvious, if you know the case.
It is Susan Battersby who was encouraged by the police to give a precise date, and she obliged them. Interestingly, this was not the time of Jeremy's call, rather it was the time that Julie came into Susan Battersby room after Jeremy's call - though Jeremy's call was brief, hence the significance of the time given. I wonder why Julie did that? Perhaps we should pass over that question in silence, as a famous philosopher once said.
As you rightly say, the flatmates were all over the place with times, even suggesting it could have been any time between 2.00 and 3.30 a.m.! But that doesn't help the prosecution case, does it. It means Jeremy could be as right as the flatmates about when he rang Julie, and in that regard, you have not a leg to stand on.
Anyway, whichever way you look at it, if you are saying Jeremy has staged the call, then it doesn't add up.
If you want to change your story and say that Jeremy just made up the call from Nevill out of thin air, fine. In that case, you don't need June's bike, Jeremy can just go back on foot.
