It looks like it was just added without any thought about how it would be used. It seems to have been stuck on to fit around the existing road rather to integrate with it.
It’s not going to encourage cycle use along it in my view. Stop, start, stop, start over a short stretch then back onto the road!
A proper well thought cycle track all the way to Harwell would be great, but as it is I will still be using the road on my commute.