Then we'll have to agree to disagree because I believe it may be potentially relevant. Since there may be a reason why it is omitted from such notes and diaries (i.e. other than the reason that it simply didn't happen).
Sorry, but I think you are right, we will have to disagree. Basically (in my opinion) there is no evidence whatsoever that any of the relatives stated that Jeremy had been seen on the night of the murders crouching behind a hedge. Nothing, nilch, zero, zip, except for Mikes word, which quite frankly means very little to me either.
Bearing that in mind, I'm not going to enter into discussions about why something may not be recorded, when there is no evidence that the 'something' happened in the first place.
One final observation, if the relatives lied about a lorry driver witnessing Jeremy crouched behind a hedge, then how is it possible that the police managed to trace that lorry driver? I think if you substitute 'complete bollocks' instead of where it says red herring, you may be a little closer to reality.