A working machine comprising: a working arm (6, 9), wherein the working arm (6, 9) comprises a boom and a dipper arm; a hitch arrangement (7, 10) attached to the working arm and configured to be removably secured to a working implement (8, 11), wherein the hitch arrangement (7, 10) is attached to a distal end of the dipper arm; one or more sensors configured to determine a likely orientation of a working implement (8, 11) secured to the hitch arrangement (7, 10) by sensing an orientation of the hitch arrangement, and to output a signal indicative of the orientation of a working implement (8, 11) secured to the hitch arrangement (7, 10) with respect to gravity; a control module configured to receive the signal from the one or more sensors and to perform a safety function in response to receipt of the signal such that the safety function is performed if the orientation of a working implement (8, 11) secured to the hitch arrangement (7, 10) with respect to gravity is an unpermitted orientation; and a user operable control coupled to the hitch arrangement (7, 10) and configured to actuate a closure of the hitch arrangement (7, 10) between an open and a closed position, the closure being adapted to secure a working implement (8, 11) to hitch arrangement (7, 10) releasably, wherein the safety function includes preventing the closure arrangement from moving from a closed to an open position, characterised in that: the one or more sensors comprise a first sensor configured to issue a signal indicative of a position of at least part of the hitch arrangement (7, 10) with respect to the dipper arm, and a sensor arrangement configured to issue a signal indicative of an orientation of the dipper arm with respect to gravity. a working arm (6, 9), wherein the working arm (6, 9) comprises a boom and a dipper arm; a hitch arrangement (7, 10) attached to the working arm and configured to be removably secured to a working implement (8, 11), wherein the hitch arrangement (7, 10) is attached to a distal end of the dipper arm; one or more sensors configured to determine a likely orientation of a working implement (8, 11) secured to the hitch arrangement (7, 10) by sensing an orientation of the hitch arrangement, and to output a signal indicative of the orientation of a working implement (8, 11) secured to the hitch arrangement (7, 10) with respect to gravity; a control module configured to receive the signal from the one or more sensors and to perform a safety function in response to receipt of the signal such that the safety function is performed if the orientation of a working implement (8, 11) secured to the hitch arrangement (7, 10) with respect to gravity is an unpermitted orientation; and a user operable control coupled to the hitch arrangement (7, 10) and configured to actuate a closure of the hitch arrangement (7, 10) between an open and a closed position, the closure being adapted to secure a working implement (8, 11) to hitch arrangement (7, 10) releasably, wherein the safety function includes preventing the closure arrangement from moving from a closed to an open position, characterised in that: the one or more sensors comprise a first sensor configured to issue a signal indicative of a position of at least part of the hitch arrangement (7, 10) with respect to the dipper arm, and a sensor arrangement configured to issue a signal indicative of an orientation of the dipper arm with respect to gravity.