The annual service as we know it today was created by the caravan manufacturers (Bailey first with their bolted construction which required annual checking and torque testing. After some time they realised the torque issue was not a problem, so the checks were dropped). The compulsory annual inspection was required to support the extended warranty, which was more or less forced upon the manufacturers by dissatisfied retailers and customers. Discovering the water ingress before it had done too much damage would reduce the manufacturer's warranty liability, but the cost? The answer was to get the customer to pay for it. The damp test became part of a service which is a padded out list of rather simplistic checks, most of which we all do every time we use the caravan. Today, the damp test as we call it isn't even done on some caravans, and reduced on others. The service technician training and AWS scheme is a nice little earner for its creator and the content of the service list, and much more is controlled by NCC Ltd. Preventive Maintenance is a good thing and for anything on the road a safety matter to be taken seriously, but most of the content of the annual service is nothing to do with that.