According to Pc Cracknell, he was on duty on 7 August 1985 with Pc Norcup, forming the crew of car CA5, when at 3.33am, as a result of information received whilst at Chelmsford Police Station in the Control Room, they were requested to attend White House Farm. As he was in the same control room as Pc West, it seems that there must have been some discussion in the control room that eventually resulted in the despatch of CA5. A few minutes later, Bonnett was presumably informed that CA5 was on its way, as he logged a time of 3:36am for this. For some reason, CA5 was not despatched very quickly and averaged only around 25 mph for the trip to WHF. What delayed them has never been explained.
Car CA6 arrived at WHF, according to Bonnett's log, at around the same time as car CA5. I'll try to spot more information about CA6.