Bernie, NO, you do not have a fault............... the centre diff allows the front wheels to turn, even when the handbrake is on, this is exactly why land rover supply a chock with each vehicle for use when jacking, imagine changing a rear wheel, the vehicle is on a hill lets say, you raise the rear to change ne wheel, the other wheel can now turn due to one of the real wheels being off the ground, the front wheels can turn cos the handbrake doesn;t work on them, and hey presto, your land rover falls off the jack.... so, when jacking, use the chock...!!