Thanks for the tip on the Reserved sign @Davenjo
Went out for the day in the van to tour round Hannover and when we got back the site was nearly full. Sure we would have lost our pitch had it not been for this.
The Germans had never seen one before and were all very interested as to where they could get one.
I think a few were quite miffed as we were in an excellent spot and our sign stopped them from pinching it.