I think in a similar way to the County 6x4 and 6x2 Trader, it was built as a 3 axle and available new direct from a Ford Dealer rather than buy the truck then have it converted. Also I believe the County was covered under the Ford warranty system as it used all Ford parts for the build so all service parts were available from the Ford dealer. All Wheel Drive Camberley may have had a similar arrangement. I seem to remember being told that this incarnation of All Wheel Drive were tied up with Clark equipment and may have then been hoovered up by Michigan in the 1960s. AWD in Dunstable I thought only appeared in the late 70s / early 80s but like wearing orthopiedic shoes, I stand to be corrected!
Oddly All Wheel Drive Camberley were based only about 5 miles away from County Commercial Cars.
The deeper oi' ploughs, the 'arder she grunts.