"No vanners allowed". ... I was surprised to learn that it was a shortened term for cravaners

I wonder if there is a linguistic connection between "cravaners" and "caravans".

I remember reading an Egyptian proverb some years back [Anwar Sadat responding to homeland critics of his Camp David peace initiative]:

"The dogs will bark but the caravan keeps rolling along."

In his case, alas, there was more than just bark in those "dogs".