NB it's possible he saw something the CCTV scope didn't reach!!
I have said before so sorry to repeat but I think Claudia told DO who she spent all night with
and its likely DO knows him. Given that DO admits he does a bit of workplace bantering I think he would have no problem bantering up Claudias disclosure of an all night session with this man and I suspect this did not go down well especially if the man was in a relationship or married.
Having got the response he did DO probably realised he had put his foot in it and it was more than likely that the s*** was going to hit the fan. Thats why he didnt offer Claudia a lift as she would have more than likely had a go at him and taking a completely different route would mean he would have distanced any contact with her until they both arrived at work
I think the sighting of the car with the door open (reported as either the passenger or driver door) and a man and a women appearing to be arguing is a valid sighting and this is possibly the man who Claudia had previously spent the night with. He was travelling that route (either to work or study) with the knowledge that Claudia would be walking to work and intented to confront Claudia about her disclosure seeing her between her house and costcutters (which is why she didnt appear on their cctv) he picked her up (knowing him she would willingly get in the car) on the journey he confronted her ( or continued the argument which had started when Claudia rang him from the public phone box ( as Eyeswideopen suggested)the prev afternoon regarding what she had told DO and I suspect she would told him to stop the car Ive had enough Im getting out which is why the car appears part on road part on verge I suspect the the verbal exchange continued as she exited the car and crossed the road. Impulsively jumped out the car leaving his door open and continued an escalating argument. The argument that spiralled out of control with Claudia possibly being struck unconcious and rolling down the bank.I notice that the location of the sighting of the two people arguing was on some sort of winding junction enabling the man to to just turn down into it and place Claudia in the car. In a panicked state he possibly strangled her in the car he then drove to the River Ouse waters edge and disposed of the body.
This is just my opinion of events..
Apologises I went to hit save draft and instead it appears to have posted grrhh.
In finishing
I beleive it is possible CL could have left by her front door the cctv camera in the house opposite was prone visual problems with condensation on the window and given the passing traffic on that road its possible that she could have not been clearly identified
I my opinion DO did not reveal the mystery man to the police in the first instance as he realised that it could be seen that it his actions that triggered the tragic events of the day..
I thank you for Eyeswideshut excellent sleuthing re a possible public phonebox being used that afternoon enabling me to fill in a possible piece of important info .. If this man was the man Claudia spent the night with its possible she contacted via the public phone because she didnt want her number appearing on his phone ( because in a relationshipship or married) or she didnt have his number at all and was trying to contact him through his workplace.
The siting of two people arguing on University road and the search dogs tracing Claudias scent to the River Ouse waters edge completes a very credible scenario for me
These are just my opinions of what may have happened only time will tell how things really did play out that day