Just been the "Caretaker" for a mates Bailey Unicorn S3, and had it serviced today, and although its been on his driveway, unused, for a year now and I have only been into it three times, the damp levels throughout the van were at 8% very nice.
The service engineer suggested that cat litter is good for anyone with damp, as it will absorbe upto 10 times its own weight.
Going back tomorrow and check my £20 meter to his readings.