I don't know. It was heavy traffic and poor conditions. The police thought she left in a hurry and it really does look like that was the case. I still think her intention was a night in and something unexpected cropped up. Of course there are no witnesses to anything up until those who may have seen Janice's car in the layby.If it was Conner, or someone with a similar MO, then presumably he would have been hiding out there, hoping to encounter a lone female.
It's difficult to work out why Janice would head to Clopton on her own. Is a spur of the moment decision to live a little and head up there completely unrealistic? It was usually only a 90 minute drive in good conditions.
You also have the issue of how someone was waiting in the layby. By all accounts not really one you could walk to easily. Would have required walking across farmland and fields in that weather.