I'm troubled by him asking the police to pick him up: this does sound horribly like trying to establish an alibi.
But back in 1985 I lived in a village which still had a police house and a policeman and his family living in it: it occurs to me that we had that phone number down on the list of emergency numbers by the phone and I'd have been more inclined to phone him than 999 to a national level call centre if I wanted help quickly: rural roads were far crappier back then to navigate. It's easy to forget the difference it made having closer access to police officers. A local would be more likely to find the remote farm as well.
Would he perhaps have phoned Witham because his father was a Magistrate there?
I suppose he was vindicated for dialling these police stations rather than 999 as ultimately these are indeed where cars were dispatched from. I've checked on Mappy.com
http://en.mappy.com/#/2/M2/TItinerary/IFRChelmsford%20CM1%201%20-%20SS5%206|TOTolleshunt%20D'Arcy%20CM9%208|GP1.355/N0,0,-0.09691,51.51666/Z7/And the journey from Chelmsford is via Witham and is 20 miles to Tollshunt d'Arcy, via the A12 taking 35 mins at normal speeds.
The journey from Witham is 10 miles and would take 23 mins. Chris Bew was dispatched from Witham but reckons he got there 20mins before Bamber, which is rather odd given he overtook him on the way there and the whole journey from Goldhanger to Tollshunt d'Arcy is only 6 mins at normal speeds
https://groups.google.com/forum/m/#!topic/uk.legal/HeHfdy_asxII'm not quite sure how they came to be overtaking Bamber, given the most direct route from Witham is through country lanes via Tolleshunt Major and the quickest is up the A12 and down via Tiptree - and neither seems to afford much opportunity to overlap Bamber's route except the very end, which would mean he would arrive only a minute or two after them, not 20 mins later.
This Bew character seems rather shifty to me.