A telescopic boom conveyor apparatus including a boom that carries a conveyor, a support structure for the boom, a rear pivot joint that connects a rear end of the boom to the support structure, a pivot drive that controls pivoting movement of the boom about the rear pivot joint, an operator cage attached by a front pivot joint to a front end of the boom; wherein the boom conveyor includes a rear boom section that is connected by the rear pivot joint to the support structure, and a front boom section that is connected by the front pivot joint to the operator cage, wherein the front and rear boom sections are telescopically adjustable to adjust the length of the boom conveyor; characterised by a levelling system that controls rotation of the operator cage about the front pivot joint, wherein the levelling system includes a flexible cord that is attached to the operator cage and extends from the cage towards the rear end of the boom, and a level adjusting device that is attached to the support structure adjacent the rear end of the boom and engages an adjusting portion of the cord, whereby during pivoting movement of the boom the level adjusting device controls longitudinal movement of the cord relative to the boom so as to apply a levelling adjustment to the operator cage; wherein the levelling system includes a compensating mechanism that compensates for changes in the length of the boom conveyor; wherein the compensating mechanism includes a first compensating guide element located towards a rear end of the front boom section, a second compensating guide element located towards a front end of the rear boom section; and wherein the cord includes a front portion that extends from the operator cage to the first compensating guide element, an intermediate portion that extends from the first compensating guide element to the second compensating guide element, a rear portion that extends from the second compensating guide element to a return mechanism that is located towards the rear end of the boom conveyer, and a return portion that extends forwards from the return mechanism and is attached to the front boom section. characterised by a levelling system that controls rotation of the operator cage about the front pivot joint, wherein the levelling system includes a flexible cord that is attached to the operator cage and extends from the cage towards the rear end of the boom, and a level adjusting device that is attached to the support structure adjacent the rear end of the boom and engages an adjusting portion of the cord, whereby during pivoting movement of the boom the level adjusting device controls longitudinal movement of the cord relative to the boom so as to apply a levelling adjustment to the operator cage; wherein the levelling system includes a compensating mechanism that compensates for changes in the length of the boom conveyor; wherein the compensating mechanism includes a first compensating guide element located towards a rear end of the front boom section, a second compensating guide element located towards a front end of the rear boom section; and wherein the cord includes a front portion that extends from the operator cage to the first compensating guide element, an intermediate portion that extends from the first compensating guide element to the second compensating guide element, a rear portion that extends from the second compensating guide element to a return mechanism that is located towards the rear end of the boom conveyer, and a return portion that extends forwards from the return mechanism and is attached to the front boom section.