It might mean:
the wife is barren so they have 'no children'
the husband is infertile so they have 'no children'
Or it could mean:
No children have ever crossed the threshold of the caravan
Or, if you are interested in the caravan and wanted to view it, it might mean no children will be allowed in close proximity of the caravan
Or, it might mean, no children are included in the price of this caravan
Or, it could mean this caravan is not suitable for children
Lisa
It might mean:
the wife is barren so they have 'no children'
the husband is infertile so they have 'no children'
Or it could mean:
No children have ever crossed the threshold of the caravan
Or, if you are interested in the caravan and wanted to view it, it might mean no children will be allowed in close proximity of the caravan
Or, it might mean, no children are included in the price of this caravan
Or, it could mean this caravan is not suitable for children
Lisa