On a bicycle it only takes 11-15 minutes to get to White House Farm from 9 Head Street in Goldhanger.

Farmhouse just a few hundred metres east of red pointer.
If you were the killer, and you were riding away from the scene on a push bike, would you travel on the main road to get from point A to Point B? No, of course you wouldn't. Would you have lights front and rear of the bike as you rode along? No, of course you wouldn't...
DI Wilkinsons evidence was part of the prosecutions file that they built up to use against Jeremy, and therefore it has to have a direct bearing upon the claim that if Jeremy was the killer, how he got from one place to the other - 1 hour and 3 minutes by bycicle, 2 hours and 25 minutes walking...