Open the tailgate and ease the headlining down at the back. It is only held in place by the rubber seal which runs round the rear hatch opening. You will then be able to get your hand in and unscrew the one large nut which holds the aerial in place. There is also a connecter in the aerial lead quite close the the base which needs to be disconnected to facilitate removal. To replace the headlining simply tuck it back into the rubber seal.