It solves one question anyway, if Jeremy has bionic eyesight and can see in the dark that must be how he managed to ride the bike across the fields in the pitch darkness.

I read there are three bike routes to the house that avoid the main roads. A fit young farmer should be able to do this.
Mugford says she first saw the bike at Jeremys a few days beforehand. Jeremy did not confirm or deny this in the police interview transcripts.
Jeremy certainly did not get the bike for himself. He would not be seen dead on it. Why would Mugford need it ? She lived in Lewisham & would have been driven by Jeremy when visiting his cottage.