I reckon the photographer would have been booked for perhaps 1 or 2 hours for the dawn shots then the "on-the-road" shots. The other cars were still owned by factories/agents, the KR was privately owned. The Trade would have been VERY keen to get the publicity and ensured they were there on time, the privateer(s) in the KR perhaps not so bothered, and perhaps overslept, were delayed or took a scenic route, missing the dawn arrival and line-up shots, but arriving in time for the action ones.