DV is sceptical of the reliability of this account because the witness took several weeks to come forward with it and then apparently added nothing that he could not have seen in the TV reconstruction.
I'm a bit sceptical of the 37SR sightings generally because you only ever hear the one where it's Cannan outside at 1pm and QED. In the various TV documentaries you never hear it mentioned that she might not even have taken the keys; that she left no trace of having been inside; that other witnesses gave different descriptions; that HR later ID'ed a 45 year old man as the late-20s-ish Mr Kipper; that several of the supposed "corroborating" witnesses actually undermine the 1pm sighting by seeing something different perhaps as late as 4pm; that several other sightings in 37SR are never explained, such as the
two white Fiestas seen or the two men seen waiting in a dark car (JC and JT?).
Interestingly, DV and the police agree that
BW's sighting at 2.45pm didn't happen and she got the day wrong, but for different reasons - DV thinks SJL was already dead at the PoW by that time, while the police preferred to believe WJ who said the car was in Stevenage Road at that time, not in FPR.
Of all the sightings, I personally reckon only BW's is accurate. SJL possibly met someone at 37SR, but never went inside and was instead persuaded to drive someone elsewhere. The logistics and car management required for this suggest to me that any Mr Kipper had an accomplice.