It was all part of the family and EP creating a back story. As I have posted before they had to produce an accomplice or a means for JB to make both calls. There was a chance that the defence might go for a call from NB but as we know that never materialised, because West testified to his second statement not his log and the defence were too busy trying to undermine the SM evidence. They also had to fabricate the entry method and the banging of the kitchen window it to close it. This was also part of the back story for how JB manged to exit a supposedly secure building. It was AE who came up with that ploy. I hope Adam does not resurrect the AM thread
Oh yes,there is no doubt it was all a back story Bubo.Why on earth would the relatives be looking into a bike being used within days of the murder? For one thing,how did they know that all other transport had been ruled out by the police investigation at that stage.As you say,once all enquiries were concluded with no witness seeing Bamber leave his house that night the police had to come up with a way that JB could get back home from the WHF in around ten minutes incase the jury believed JB was telling the truth about a call from Nevill,hence the bike was needed,walking would have taken far too long.
But as you say,when the jury were told that it was Sheilas blood only in the silencer the phone calls seemed of little importance.