It would obviously have been different if his van was blue! What relevance is that?

As it’s a CL, he must be a fellow club member unless the site owner is breaking the rules. It’s also entirely up to the site owner whether dogs are allowed to be loose.

Neither the white van or his partners Suzuki car were fitted with a towing bracket........ (I checked), so how the quite old caravan got there in the first place??

As for the dogs, the owner of the site asked me to make certain our dogs were under control at all times as there are sheep grazing in the adjacent field, so this person, letting his dogs roam freely and not watching where they were or what they were doing was patently out of order!!

Out of order in your view but the site owner may have been quite happy. This isn’t a club site and the CL owner can set his own rules, albeit one rule for one person and another for the rest.

Having sleuthed around it would seem you think the other van may not have been owned by a club member. The CL dept at the club is the place to report breaches of rules. 

One way is to vote with your feet/wheels and alert others to the issue. You’ve done that. 👍🏻