Just taken my cover off the caravan, it's been on since November 2005. Due to family illness the caravan was not used at all last year and the cover remained on even through the very hot summer of 06.
To be honest I expected some problem but the caravan was in tip top condition, not a mark on it and as clean as the day it was fitted.
the cover was in the caravan when we bought it second hand, it's aProtec and withoutdoubt an invaluable bit of kit. It will be going on at the end of year once again.