Mal,
When I picked up my new Swift Conqueror from my dealer Golden Castle Caravans at Chelenham in January I was asked did I want my caravan treating externally with a special coating. A firm came to the dealer and treated the caravan prior to delivery. Once treated the caravan never needed polishing again, just washing. The cost put me off but some people were having their caravans treated. Give their service department a ring on 01452 713366 and ask for Jackie, she is the service manager.
Hamer