He didn't stop Reader.
I expect you're right.
It's a bit odd that some statements suggested that CA7 waited 3 to 4 minutes for him to arrive. There's wasn't much reason for exaggerating this time and yet estimating Jeremy's speed as 30mph when he was overtaken. Had CA7 averaged 50 mph for the final mile, whilst Jeremy averaged 25 mph, CA7 would have been waiting where they stopped for just 72 seconds before Jeremy got there (because CA7 would have taken 72 seconds, whereas Jeremy would have taken 144 seconds). None of the statements of the officers in CA7 suggest Jeremy was asked anything at the time in relation to how long it had taken for him to catch them up.
Ps Bews seemed to have realized that the estimates didn't make sense, as his statement of 19/09/85 corrected his earlier statement by saying the 3 to 4 minute wait was timed from when Jeremy was overtaken rather than from when CA7 parked. However, Pc Saxby and Pc Myall didn't make this correction, and the correction is bizarre anyway as there was no reason to estimate the duration of that interval and the duration still seems exaggerated.