A controller for controlling a driveline of a motor vehicle to transition between first and second modes of operation, wherein a first group of one or more wheels (12, 13) and not a second group of one or more wheels (14, 15) is connected to a torque transmission path from the prime mover means when the driveline is in the first mode of operation and both the first and second groups of one or more wheels are connected to the torque transmission path when the driveline is in the second mode of operation, wherein the second group of one or more wheels is connected to the torque transmission path by means of an auxiliary portion comprising first and second releasable torque transmitting means and a prop shaft, the first releasable torque transmitting means being operable to connect a first end of the prop shaft to the torque transmission path, the second releasable torque transmitting means being operable to connect a second end of the prop shaft to the second group of one or more wheels, the controller being configured to: control the auxiliary portion to switch the driveline between the first and second modes of operation such that in the first mode the prop shaft is disconnected from both the torque transmission path and said second group of one or more wheels; characterised in that the controller is further configured to control the driveline to transition from the first mode to the second mode when a second mode trigger condition is met, the second mode trigger condition including the requirement that the magnitude of the value of a vehicle operating parameter of a first set of one or more vehicle operating parameters is less than or greater than a first threshold value; and control the driveline subsequently to transition from the second mode to the first mode when a first mode trigger condition is met, the first mode trigger condition including the requirement that the magnitude of the value of said vehicle operating parameter of the first set is greater than or less than a second threshold value, the second threshold value having a value different from the first threshold value, wherein the subsequent transition from the second mode back to the first mode is prevented unless the second mode trigger condition has not been met for a time period that is greater than a disconnect delay period. control the auxiliary portion to switch the driveline between the first and second modes of operation such that in the first mode the prop shaft is disconnected from both the torque transmission path and said second group of one or more wheels; characterised in that the controller is further configured to control the driveline to transition from the first mode to the second mode when a second mode trigger condition is met, the second mode trigger condition including the requirement that the magnitude of the value of a vehicle operating parameter of a first set of one or more vehicle operating parameters is less than or greater than a first threshold value; and control the driveline subsequently to transition from the second mode to the first mode when a first mode trigger condition is met, the first mode trigger condition including the requirement that the magnitude of the value of said vehicle operating parameter of the first set is greater than or less than a second threshold value, the second threshold value having a value different from the first threshold value, wherein the subsequent transition from the second mode back to the first mode is prevented unless the second mode trigger condition has not been met for a time period that is greater than a disconnect delay period.